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What is the risk of hearing loss for someone standing next to a shooter? Friends, spouses, children, and other shooters are often present during hunting and recreational shooting activities, and these bystanders seem likely to underestimate the hazard posed by noise from someone else's firearm. Hunters use hearing protection inconsistently, and there is little reason to expect higher use rates among bystanders. Acoustic characteristics and estimates of auditory risk from gunfire noise next to the shooter were assessed in this study. This was a descriptive study of auditory risk at the position of a bystander near a recreational firearm shooter. Recordings of impulses from 15 recreational firearms were obtained 1 m to the left of the shooter outdoors away from reflective surfaces. Recordings were made using a pressure-calibrated 1/4 inch measurement microphone and digitally sampled at 195 kHz (24 bit depth). The acoustic characteristics of these impulses were examined, and auditory risk estimates were obtained using three contemporary damage-risk criteria (DRCs) for unprotected listeners. Instantaneous peak levels at the bystander location ranged between 149 and 167 dB SPL, and 8 hr equivalent continuous levels (LeqA8) ranged between 64 and 83 dB SPL. Poor agreement was obtained across the three DRCs, and the DRC that was most conservative varied with the firearm. The most conservative DRC for each firearm permitted no unprotected exposures to most rifle impulses and fewer than 10 exposures to impulses from most shotguns and the single handgun included in this study. More unprotected exposures were permitted for the guns with smaller cartridges and longer barrel length. None of the recreational firearms included in this study produced sound levels that would be considered safe for all unprotected listeners. The DRCs revealed that only a few of the small-caliber rifles and the smaller-gauge shotguns permitted more than a few shots for the average unprotected listener. This finding is important for professionals involved in hearing health care and the shooting sports because laypersons are likely to consider the bystander location to be inherently less risky because it is farther from the gun than the shooter.
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Auditory Risk to Unprotected Bystanders Exposed to
Firearm Noise
DOI: 10.3766/jaaa.22.2.4
Gregory A. Flamme*
Michael Stewart
Deanna Meinke
James Lankford§
Per Rasmussen**
Abstract
Background: What is the risk of hearing loss for someone standing next to a shooter? Friends, spouses,
children, and other shooters are often present during hunting and recreational shooting activities, and
these bystanders seem likely to underestimate the hazard posed by noise from someone else’s firearm.
Hunters use hearing protection inconsistently, and there is little reason to expect higher use rates among
bystanders. Acoustic characteristics and estimates of auditory risk from gunfire noise next to the shooter
were assessed in this study.
Research Design: This was a descriptive study of auditory risk at the position of a bystander near a
recreational firearm shooter.
Data Collection and Analysis: Recordings of impulses from 15 recreational firearms were obtained 1 m
to the left of the shooter outdoors away from reflective surfaces. Recordings were made using a pressure-
calibrated 1/4 inch measurement microphone and digitally sampled at 195 kHz (24 bit depth). The acous-
tic characteristics of these impulses were examined, and auditory risk estimates were obtained using
three contemporary damage-risk criteria (DRCs) for unprotected listeners.
Results: Instantaneous peak levels at the bystander location ranged between 149 and 167 dB SPL, and
8 hr equivalent continuous levels (L
eqA8
) ranged between 64 and 83 dB SPL. Poor agreement was obtained
across the three DRCs, and the DRC that was most conservative varied with the firearm. The most con-
servative DRC for each firearm permitted no unprotected exposures to most rifle impulses and fewer than
10 exposures to impulses from most shotguns and the single handgun included in this study. More unpro-
tected exposures were permitted for the guns with smaller cartridges and longer barrel length.
Conclusions: None of the recreational firearms included in this study produced sound levels that would be
considered safefor all unprotected listeners. The DRCs revealed that only a few of the small-caliberrifles and the
smaller-gauge shotguns permitted more than a few shots for the average unprotected listener. This finding is
important for professionalsinvolved in hearing health care and the shootingsports because laypersons are likely
to consider the bystander location to be inherently less riskybecause it is farther from the gun than the shooter.
Key Words: Auditory risk, firearms, impulse noise, noise exposure, prevention—hearing loss
Abbreviations: AHAAH 5Auditory Hazard Assessment Algorithm for Humans; ACP 5automatic Colt
pistol; BOSS
â
5Ballistic Optimizing Shooting System; DRC 5damage-risk criterion; HPD 5hearing
protection device; MPE 5maximum permissible exposure; SEL 5sound exposure level
The use of firearms and participation in recrea-
tional hunting vary as a function of geographical
location and culture. In the United States, 18.6
million individuals over the age of 16 yr hunted an aver-
age of 18 days a year during the 5 yr period from 2002 to
2006. Youth hunters 6 to 15 yr of age are estimated to
number 1.6 million (U.S. Fish and Wildlife Service,
2006). The National Shooting Sports Foundation (2009)
*Western Michigan University, Kalamazoo; Central Michigan University, Mount Pleasant; University of Northern Colorado, Greeley; §Northern
Illinois University, DeKalb; **G.R.A.S. Sound and Vibration A/S, Holte, Denmark
Gregory A. Flamme, Ph.D., Western Michigan University, Department of Speech Pathology and Audiology, 1903 Michigan Ave., Kalamazoo, MI
49008; Phone: 269-387-8067; Fax: 269-387-8044; E-mail: greg.flamme@wmich.edu
J Am Acad Audiol 22:93–103 (2011)
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reports that there are 30 million active sports shooters
(hunters, cowboy shooters, etc.) over age seven in the
United States. In addition, there are an estimated 20.3
million active target shooters (skeet, trap, and sporting
clays) in the United States (National Shooting Sports
Foundation, 2009). These statistics do not include the
“occasional shooter” who may fire a weapon at gun shows,
guest resort activities, rural farms/ranches, or outdoor
fundraising/sporting events. Friends, family members,
spectators, and instructors may accompany these
“shooters” and be indirectly exposed to firearm impulses
that potentially put them at risk of acoustic trauma.
Impulses from firearms are commonly referenced in
terms of instantaneous peak sound pressure levels. Peak
sound pressure levels typically exceed the U.S. Occupa-
tional Safety and Health Administration (1983), the
National Institute of Occupational Safety and Health
(NIOSH), the U.S. MIL-STD-1474D (U.S. Department
of Defense, 1997), and the World Health Organization
(1999) limit of 140 dB SPL (Odess, 1972; Ylikoski et al,
1995; Kardous et al, 2003; Murphy and Tubbs, 2007)
and can potentially lead to noise-induced hearing loss
(Patterson and Hamernik, 1992; Chan et al, 2001). How-
ever, the potential damage to the auditory system is not
fully represented by peak SPL values. Sound exposure
characteristics such as the total energy contained in
the impulse, frequency spectrum, and pressure wave
(i.e., A) and pressure envelope (i.e., B) durations of the
time waveform are important considerations in terms
of describing auditory risk from firearms (see Flamme
et al, 2009a, for a review; Committee on Hearing, Bioa-
coustics, and Biomechanics [CHABA], 1992). Briefly, the
A-duration is the time interval between the initial pres-
sure rise of the impulse and the moment the pressure
passes through ambient. The B-duration is the time
interval during which the envelope of the signal resides
within 20 dB of the peak pressure.
Firearm impulse sound exposure contributes to the
poorer hearing ability and hearing handicap evident
in sports hunters when compared to nonhunters (Taylor
and Williams, 1966; Stewart et al, 2002). Nondahl et al
(2000) calculated a 7% increase in the likelihood of hav-
ing a marked high-frequency hearing loss for every 5 yr
of hunting. In addition, hunters consistently used hear-
ing protection less than 5% of the time during their
hunting activities (Wagner et al, 2006). Hunters are
more likely (62–80%) to wear hearing protection when
target shooting than when hunting (Wagner et al,
2006), and the use of hearing protection tends to be
higher among target shooters (Nondahl et al, 2000).
This tendency was also noted in police officers, who were
also more likely to consistently wear hearing protection
devices (HPDs) during job-related firearms-qualification
activities (95%) as opposed to nonoccupational shooting
activities (0% [Hughes and Lankford, 1992]). In workers
exposed to occupational noise, the additional exposure to
firearm noise can be expected to lead to a greater de-
gree of hearing loss than for peers without exposure
to firearm noise (Prosser et al, 1988; Clark, 1991;
Kryter, 1991; Pekkarinen et al, 1993; Stewart et al,
2001; Neitzel et al, 2004).
Exposure to firearm noise is encountered in both
occupational and nonoccupational settings. Law enforce-
ment, security, military, wildlife officers, hunting guides,
firearm and ballistics/accessory manufacturers, gun-
smiths, and firearm range personnel are occupationally
exposed to firearm noise. Recreational firearm use
encompasses the traditional hunter and target shooters
and also extends to cowboy action shooting, travel resort
shooting galleys, dog training, .50 caliber shooting asso-
ciations, gun shows, Boy/Girl Scouts, and 4-H activities.
In most if not all of these situations, a bystander may be
participating in the training and/or observing the event.
Bystander firearm noise exposure has primarily been
assessed in the occupational shooting range environ-
ment. Recently, Kardous et al (2003) recorded a time-
weighted average noise exposure of 108 dBA (19,282%
daily dose) for an observer in an indoor shooting range
using the NIOSH (1998) noise sampling criteria. While
these authors recognize the limitations of noise dosime-
ter instrumentation in terms of capturing the impulse
noise source, the results are valid in terms of document-
ing overexposure for the bystander.
While there are few data concerning the auditory risk
to those near the shooter, there is evidence to suggest
that the noise exposure is dependent upon the location
of the listener (or bystander). Plomp (1967) showed that
the Fusil Automatique Le
´ger assault rifle produced
lower peak levels 180 degrees from the line of fire than
at other locations. Similar results were obtained
recently with a bolt-action rifle chambered for the .22
Hornet cartridge (Rasmussen et al, 2009). The current
study was designed to measure the impulse sound lev-
els and estimate the auditory risk for persons standing
approximately 1 m to the left of a right-handed shooter.
The auditory risk for a bystander will be estimated by
using the waveform parameter–based damage-risk cri-
terion (DRC) developed by Coles et al (1967) and modi-
fied by the National Academy of Sciences Committee on
Hearing, Bioacoustics, and Biomechanics (1968); the
energy-based approach advocated by Smoorenburg
(2003); and the Auditory Hazard Assessment Algorithm
for Humans (AHAAH) developed by Price and Kalb
(1991) and described further by Price (2007).
METHOD
Firearms and Ammunition
The 15 firearms used in this study were selected to
represent a variety of those used for recreational shoot-
ing activities such as hunting and target practice.
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Details concerning each firearm are presented in Table
1. Photographs of the guns and ammunition are available
as supplementary data accompanying the electronic ver-
sion of this article on the publisher’s Web site (www.
audiology.org/resources/journal). The .410 gauge and
20 gauge shotguns are typically used when hunting
smaller game such as rabbits, squirrels, and some game
birds;whilethe 12 and 10gauge shotguns are favorites for
hunting waterfowl (Stewart et al, 2009), pheasant, quail,
and turkeys. The .30-06 rifle, 7 mm Remington Magnum
rifle, .45-70 rifle, and the .50 caliber muzzle-loader are
commonly used for large gamesuch as deer, elk, and bear.
According to Wagner et al (2006), the .30-06 rifles and
12 gauge shotguns are the most frequently used fire-
arms for large and small game, respectively. For tar-
get shooters, the firearm preferences are rifles (67.4%),
handguns (62.5%),muzzle-loaders (24.5%),and shotguns
(20.4% [Southwick Associates, 2009]). The AR-15, the
M14,and the Auto-Ordnance (Thompson)1927-A1Model
T1 “Tommy gun” rifles are civilian versions of military
models and can be used for hunting but are typically used
for target practice. The .22 caliber handgun is also used
primarily for target practice.Three rifles had commercial
barrelmodifications(muzzle brake, compensator,or flash
suppressor), and measurements were obtained with
these in place. These devices are designed to improve
shooting accuracy and reduce recoil; however, installing
amuzzlebrakeon a firearm will increase peak sound pres-
sure levels when thegun is fired. The ammunition used in
the firearms in this study included a wide variety of com-
mercially available cartridges typically used for hunting
and target practice activities.
Instrumentation
Impulse recordings were made using a 1/4 inch prepo-
larized pressure-calibrated microphone (G.R.A.S. Type
40BD) having an essentially flat frequency response
through 70 kHz, oriented at grazing incidence to the
sound source. Microphone output was conditioned by a
G.R.A.S. Type 26AC preamplifier and a G.R.A.S. Type
12AA power supply and routed to a Tucker-Davis Tech-
nologies real-time processor (RP2.1). The real-time pro-
cessor was configured to perform 24 bit analog-to-digital
conversion at a 195 kHz sample rate prior to storage in a
memory buffer and subsequent transfer and scaling into
Pascal units in MATLAB.
Data Analyses
After recordings were transferred to the analysis
computer, impulse baseline corrections were made by
Table 1. Description of Recreational Firearms and Ammunition Used in the Measurement of Impulse Noise
Manufacturer Model Gauge/Caliber Cartridge/Bullet Action
Barrel Length
(inches)
Rifles
Winchester Model 70 7 mm Remington Magnum 140 grain bolt action 26 with BOSS
Remington 742 Woodsman .30-06 165 grain semiautomatic 18
Remington 742 Woodsman .30-06 165 grain semiautomatic 22
Ruger Model 1S .45-70 300 grain single shot, lever 22
Thompson/Center Encore Pro Hunter .50 250 grain with
150 grain powder
muzzle-loader 22
Rock River Arms M14 7.62 351 mm (.308) 150 grain semiautomatic 24 with flash
suppressor
Colt AR-15 5.56 345 mm (.223) 60 grain semiautomatic 20
Auto-Ordnance
(Tommy Gun)
1927-A1 Model T1 .45 ACP 230 grain semiautomatic 16.5 with
compensator
Shotguns
Remington SP10 10 gauge 3.5 inch semiautomatic 28
Remington 11-87 slug gun 12 gauge 3 inch copper solid semiautomatic 21
Remington 11-87 turkey gun 12 gauge 3 inch turkey load semiautomatic 21
Remington
a
11-87 standard 12 gauge 3 inch duck load semiautomatic 26
Remington
a
11-87 standard 12 gauge 2.75 inch field load semiautomatic 26
Mossberg 20 gauge 2.75 inch pump 26
Mossberg
b
.410 caliber 3 inch bolt 24
Mossberg
b
.410 caliber 2.5 inch bolt 24
Handgun
Ruger Bearcat .22 Long Rifle 40 grain revolver 4
a
Same gun.
b
Same gun, with and without external choke.
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subtracting the mean value during a silent period in
the waveform from all points on the recording. Each
impulse was then analyzed independently using
MATLAB software routines developed in the NIOSH
Taft Laboratories (Cincinnati, Ohio). Risk estimates
were calculated in terms of maximum permissible expo-
sure (MPE) via the three DRCs for a listening condition
in which the adult bystander was directly facing the
sound source (i.e., grazing incidence to the ear). The
MPE metric represents the highest number of expo-
sures allowable without exceeding the exposure limits
defined within the DRCs. We judged the median to be
the best indicator of MPE for each firing condition,
while ranges are also reported in the results that follow.
The DRCs included the Coles/CHABA (Coles et al,
1967; CHABA, 1968) approach based on waveform
parameters, the Smoorenburg (2003) approach based
on A-weighted energy in the impulse, and the AHAAH,
developed by Price and Kalb (1991), using a physiolog-
ical model of the ear (Price, 2007). A detailed review of
these DRCs has been presented elsewhere (Flamme
et al, 2009a), but prior comparisons of these DRCs
(Flamme et al, 2009a; Flamme et al, 2009b) have
revealed that there are substantial differences in
MPE determined by these DRCs. The Coles/CHABA cri-
terion is most conservative for high-level impulses and
least conservative for low-level impulses, the Price/Kalb
DRC is the least conservative for high-level impulses
and most conservative for low-level impulses, and the
Smoorenburg DRC lies somewhere in the middle for
impulses less than 116 dBA sound exposure level
(SEL). The SEL represents the integrated sound level
over an averaging period of 1 sec (see Earshen, 2000,
p. 72). In this sense, SEL is similar to the 8 hr equiva-
lent continuous level, but instead of dividing the sound
energy over a time frame of 8 hr, the amount of sound
energy is divided over a 1 sec period when computing
SEL. The Smoorenburg DRC is discontinuous for
impulses with 8 hr equivalent A-weighted sound pres-
sure levels greater than 80 dB. In this range, MPE is 0
for impulses with peak levels above 116 dBA SEL but
increases to a fixed value of 50 for impulses below
116 dBA SEL and above 80 dBA 8 hr equivalent contin-
uous level (dBL
eqA8
). As suggested by Smoorenburg
(2003), a 14 dB correction was applied to the SEL limit
(i.e., 120 dB SEL) to retain consistency with the other
DRCs, which presumed that the impulse source was ori-
ented at grazing incidence to the ear. The Price/Kalb
DRC permits separate assessments of auditory risk
for listeners who are unwarned or warned that firing
is imminent. The difference between these conditions
follows a hypothesis that human listeners who know
an impulse is imminent (i.e., warned listeners) will con-
tract their middle-ear muscles in anticipation and
therefore gain some additional protection from the
high-pass filtering provided when the middle-ear
muscles are contracted. On the other hand, the mid-
dle-ear muscle contractions for unwarned listeners will
be reflexive and follow the latency characteristics of a
reflex, resulting in a contraction long after the impulse
has passed. MPEs via the Price/Kalb DRC were calcu-
lated using a maximum of 500 auditory risk units under
unwarned listening conditions (i.e., no anticipatory
middle-ear muscle contraction). We elected to use the
unwarned condition based on the results of Bates
et al (1970), which found that anticipatory middle-ear
muscle contractions cannot be conditioned in the major-
ity of human listeners.
Procedure
Aminimumoffiveshots(range55–24) were fired
from each firearm. The firearms were fired on a horizon-
tal plane in a nonreverberant open field with the shooter
in a typical standing shooting position. The microphone
was positioned with a grazing incidence 1 m immediately
to the left of the right-handed shooter to simulate a typ-
ical bystander location for civilian shooting conditions.
RESULTS
Acoustic Characteristics of Firearm
Impulse Noise
Examples of noise impulses from each type of firearm
are presented in Figure 1. For each gun, a secondary
peak caused by ground reflection lagged the primary
peak by approximately 6 msec. Standard deviations
of impulse levels were 1 dB or less for all guns except
the A-weighted peak level produced by the Remington
SP10 Magnum, 10 gauge (Table 2). Unweighted peak
levels produced at the bystander location ranged
between 149.1 dB SPL for the Mossberg .410 shotgun
and 166.5 dB SPL for the Winchester Model 70 with
the Ballistic Optimizing Shooting Systemâ(BOSS)
muzzle brake. A-weighted levels were 1.7 to 3.7 dB
lower than unweighted levels. Peak levels of shotguns
and the handgun were more affected by A-weighting
than those of rifles. A-weighted 8 hr equivalent contin-
uous levels (L
eqA8
) varied between 64.0 and 82.9 dB SPL
and corresponding sound exposure levels ranged
between 108.6 and 127.5 dB SPL.
Rifles tended to produce the highest peak levels at the
bystander location, followed by shotguns and the .22
handgun. Exceptions were the Remington SP10 Magnum
10 gauge and Remington 11-87 12 gauge slug shotguns,
which produced greater peak levels than most rifles
(see Table 2). The Remington SP10 Magnum and the
Remington11-87sluggunalsoproducedhigherpeaks
than all other shotguns. This may be related to the type
of ammunition used in these particular shotguns. The
Remington SP10 Magnum 10 gauge shotgun fired a 3.5
Journal of the American Academy of Audiology/Volume 22, Number 2, 2011
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inch cartridge as opposed to a 3 or 2.75 inch cartridge,
while the Remington 11-87 12 gauge slug shotgun fired
a cartridge with a single large (1 oz) projectile (i.e., slug)
rather than multiple smaller proje cti les (i. e., s hot ). The
.22 caliber revolver also produced higher bystander
peak levels than the 20 gauge and .410 caliber shot-
guns and the Auto-Ordnance Tommy gun, which fires
.45 caliber handgun ammunition. The higher bystander
peak levels produced by the .22 handgun, which fires
the smallest cartridge of all the firearms in this study,
may be related to the significantly shorter barrel length
and action of this firearm, which resulted in the
bystander being positioned closer to the sound source.
A comparison of the acoustic characteristics of impulses
generated by the same firearm but with different-size car-
tridges is also shown in Table 2. Three-inch cartridges
fired in the Remington 11-87 12 gauge shotgun (turkey
or duck loads) generated impulses with higher peak levels
and longer durations compared to 2.75 inch cartridges
fired by the same firearm. Three-inch and 2.5 inch car-
tridges fired in the same .410 shotgun produced essen-
tially equivalent peak levels, and B-durations, but the
smaller cartridge had shorter A-durations.
Table 2 also displays the mean durations for firearm
impulses measured in this study. Pressure wave A-
durationswere generally less than 500 msec, particularly
for smaller cartridges. Pressure envelope B-durations for
impulses ranged from 6.8 to 9.3 msec. In general, the 10
and 12 gauge shotguns produced the longest B-duration
values (approximately 9 msec), while the Winchester
Model 70 ( 7 mm Remingt on Magnum) rifle and the .22
Ruger Bearcat revolver produced the shortest and nearly
identical mean B-durations of 6.868 and 6.896 msec,
respectively.
Risk Estimates
Maximum permissible exposures, assuming no hear-
ing protection, differed across DRCs. The Coles/CHABA
DRC showed the greatest range of median unprotected
MPEs across firearms, ranging from 0.18 MPE (i.e., no
allowable unprotected exposure) for the Winchester
Model 70, 7 mm Remington Magnum, equipped with a
muzzle brake to 217 MPE for the .45 Tommy gun. The
Price/Kalb DRC produced the smallest range of unpro-
tected median MPEs, with values ranging from 4 MPE
for the Winchester Model 70, 7 mm Remington Magnum,
to 26 MPE for the .45 Tommy gun. The Smoorenburg
DRC generated median MPEs of either 0 MPE (big-bore
rifles and the M14) or 50 MPE (all other firearms).
Figure 1. Examples of individual impulses from each gun. The upper panel includes sample impulses for each rifle; examples from the
shotguns and the handgun are in the lower panel. Upper panel impulses are from the Winchester Model 70 (7 mm Magnum), Remington
#742 carbine (.30-06), Remington #742 with a 22 inch barrel (.30-06), Ruger Model 1 (.45-70), Thompson/Center Encore muzzle-loader
(.50), M14 (7.62 351 mm), Colt AR-15 (5.56 345 mm), and Auto-Ordnance Tommy gun (.45 ACP), respectively. Lower panel sample
impulses are from the Remington SP10 Magnum (10 gauge), Remington 11-87 slug gun (12 gauge), Remington 11-87 turkey gun (12
gauge), Remington 11-87 standard gun firing a 3 inch cartridge (12 gauge), Mossberg 20 gauge, Mossberg .410 caliber firing a 3 inch
cartridge, and Ruger Bearcat .22 caliber, respectively. Differences between individual examples and summary values (Table 1) are
due to rounding and the specific example selected for display.
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Rifles
The preponderance of DRCs recommended no more
than 10 unprotected exposures to impulses produced by
the rifles in this study (Fig. 2). For large conventional
hunting rifles (e.g., those firing 7 mm Magnum, .30-
06, and .45-70 cartridges), median MPEs ranged be-
tween 0 (Smoorenburg DRC) and 5 (Price/Kalb DRC).
The median MPEs for the Thompson/Center Encore .50
caliber muzzle-loader and the M14 and AR-15 rifles ranged
between 0 (M14 rifle, Smoorenburg DRC) and 50 (Thomp-
son/Center Encore and AR-15 rifles, Smoorenburg DRC).
Median MPEs for the .45 Tommy gun ranged between
26 (Price/Kalb DRC) and 217 (Coles/CHABA DRC).
Shotguns
Most of the shotguns included in this study (i.e., all
but the 10 gauge shotgun and the 12 gauge slug gun)
produced noise impulses with unprotected median MPEs
greater than 1 as estimated by all three damage-risk cri-
teria (Fig. 3). The Smoorenburg DRC generated median
MPE values of either 50 or 0 across all shotguns, while
the Price/Kalb produced median MPE values ranging
from 1 to 26 across all shotguns. The Coles/CHABA
DRC tended to produce similar MPE values as the other
two DRCs for the large-bore shotguns (10 and 12 gauge)
but calculated much larger median MPEs (300–500) for
the smaller-bore shotguns (20 and .410 gauge). In general,
Table 2. Acoustic Characteristics of Firearm Impulses at the Bystander Location
Firearm and Ammunition NVariable
Peak
(dB SPL)
A-Weighted
Peak
(dB SPL)
L
eqA8
(dB SPL)
SEL
A
(dB SPL)
A-Duration
(msec)
B-Duration
(msec)
Rifles
Winchester Model 70,
7 mm Magnum
5 Mean 166.5 164.8 82.9 127.5 519 6.868
SD 0.3 0.5 0.3 0.3 32 0.061
Remington 742 carbine,
.30-06
13 Mean 162.9 160.6 78.9 123.5 378 7.907
SD 0.4 0.2 0.2 0.2 85 0.173
Remington 742 22 inch
barrel, .30-06
24 Mean 161.6 159.4 77.7 122.3 353 8.044
SD 0.5 0.4 0.3 0.3 57 0.287
Ruger Model 1, .45-70 5 Mean 160.1 157.6 77.4 122.0 442 8.354
SD 0.2 0.1 0.7 0.7 77 0.450
Thompson/Center Encore, .50 5 Mean 159.7 157.2 75.3 119.9 427 7.396
SD 0.2 0.3 0.2 0.2 32 0.670
M14, 7.62 351 mm 5 Mean 159.0 156.4 75.6 120.2 403 7.126
SD 0.2 0.2 0.1 0.1 11 0.139
Colt AR-15, 5.56 345 mm 5 Mean 158.9 156.4 74.5 119.1 382 7.305
SD 0.1 0.2 0.6 0.6 155 0.441
Auto-Ordnance Tommy Gun,
.45 ACP
5 Mean 151.0 148.5 64.0 108.6 238 7.080
SD 0.4 0.2 0.2 0.2 25 0.609
Shotguns
Remington SP10 Magnum,
10 gauge
5 Mean 161.4 157.7 79.8 124.4 518 9.228
SD 1.0 1.2 0.4 0.4 184 2.199
Remington 11-87 12 gauge slug 5 Mean 160.1 157.1 78.2 122.8 461 8.792
SD 0.8 0.3 0.5 0.5 139 2.113
Remington 11-87 12 gauge
turkey load, 3 inch ammunition
5 Mean 156.0 153.3 73.9 118.5 300 9.205
SD 0.3 0.3 0.3 0.3 26 2.375
Remington 11-87 12 gauge
duck load, 3 inch ammunition
5 Mean 156.1 153.2 72.6 117.2 382 9.090
SD 0.4 0.6 0.3 0.3 114 0.054
Remington 11-87 12 gauge, 2.75
inch ammunition
5 Mean 152.7 149.7 68.2 112.8 230 7.904
SD 0.6 0.7 0.7 0.7 32 0.527
Mossberg 20 gauge 5 Mean 150.1 147.1 66.2 110.8 208 7.438
SD 0.4 0.4 0.3 0.3 38 0.221
Mossberg .410, 3 inch ammunition 5 Mean 149.1 145.8 64.5 109.1 382 7.750
SD 0.3 0.5 0.6 0.6 114 0.750
Mossberg .410, 2.5 inch ammunition 5 Mean 150.0 146.6 65.8 110.4 248 7.358
SD 0.4 0.6 0.7 0.7 23 0.554
Handgun
Ruger Bearcat .22 6 Mean 154.0 150.6 67.1 111.7 134 6.896
SD 0.6 0.8 0.7 0.7 10 0.098
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greater numbers of permissible exposures were observed
for shotguns firing smaller-diameter cartridges. The 10
gauge shotgun and 12 gauge slug gun had the fewest per-
missible exposures (unprotected), while the .410 caliber
shotgun had the most by all three DRCs. The two types
of ammunition used in the standard 12 gauge firearm had
a substantial effect on MPE estimated by the Coles/
CHABA risk criterion, increasing from 16 MPE with a
3 inch cartridge to 69 MPE with a 2.75 inch cartridge.
However, small differences (,1 dB) in the opposite direc-
tion were observed with the .410 gauge shotgun. Fewer
exposures were permissible with the shorter cartridge
(2.5 inch) than with the longer cartridge (3 inch) for
the Coles/CHABA and the Price/Kalb DRCs. Medians
for the Smoorenburg DRC were 50 MPE regardless of
.410 gauge shell length.
Handgun
Unprotected MPEs for the Ruger Bearcat .22 Long
Rifle caliber handgun exhibited similar trends to those
observed with the other types of recreational firearms.
Aminimumof40MPEandmaximumof86MPE(median
55) were estimated via the Coles/CHABA DRC (Fig. 3).
The Smoorenburg DRC resulted in an estimate of 50
MPE for all impulses from this gun. The Price/Kalb
DRCestimatedarangeof9to15MPE(median10).
DISCUSSION
Auditory Risk to Bystanders
The focus of this investigation was to describe audi-
tory risks for bystanders exposed to civilian firearm
noise. This study reports the acoustic characteristics
and risk estimates for firearm noise across several rifles
(N58), several shotguns (N56), and a handgun at a
single position where a bystander might typically be
located. That location was 1 m to the left of the individ-
ual firing each of the guns listed in Table 1. Although
numerous other locations could and should be assessed,
this location was chosen as a likely position for a hunt-
ing guide, firearms instructor, hunting partner, ob-
server, or additional shooter who might or might not
be an active part of a shooting event. It should also
be mentioned that these data were collected outdoors
in a nonreverberant open field without walls, barriers,
trees, or other obstructions. The magnitude of each
impulse was evaluated using unweighted instantane-
ous peak levels and A-weighted instantaneous peak lev-
els, 8 hr equivalent continuous levels (L
eqA8
), and sound
exposure levels (SEL
A
). In addition, the pressure wave
durations (i.e., A-durations) and the pressure envelope
durations (i.e., B-durations) of the impulse waveforms
were evaluated (Table 2).
Several different approaches to determining auditory
damage risk from exposure to impulse noise can be
applied (Coles et al, 1967; CHABA, 1968; Smoorenburg,
2003; Price, 2007), and the results of each can be trans-
formed into maximum permissible unprotected ex-
posures, which is simply the number of gunshot
exposures allowed for a given firearm. These can be
seen in Figures 2 and 3 for the firearms used in this
study. It is noted that the Price/Kalb model appears
to compress the range of MPEs across firearms com-
pared to the other two models. This makes it atypically
liberal relative to the other DRCs that would allow few
shots (e.g., large game rifles) and also atypically conser-
vative in cases where the other DRCs would tend to
allow many unprotected shots (e.g., the 20 gauge and
.410 shotguns). It is apparent for the rifles tested
(Fig. 2) that most MPE values ranged from 0 to 10,
whereas for shotguns tested (Fig. 3) most ranged from
0 to 50 MPE. As expected, the higher the peak sound
pressure levels, the lower the MPE for both the rifles
and shotguns. The one rifle that produced the highest
peak SPL (166.3 dB) was a bolt-action rifle with a 26
inch barrel and a BOSS muzzle brake. This particular
firearm configuration used a belted 7 mm Remington
Figure 2. Median maximum permissible unprotected exposures
for each rifle, by damage-risk criterion. Error bars represent the
range of maximum permissible unprotected exposures across
shots. Permissible exposures of 0 returned by the Smoorenburg
criterion were entered as 0.1 to permit plotting.
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Magnum cartridge (high velocity and high powder
capacity).
The higher peak SPLs for rifles may relate to the
larger powder charge and/or the higher bullet velocity
when all other variables are considered. The exception
to this generalization is the addition of porting or brakes
to the barrel of the firearm. The brake allows the muzzle
gases to escape from openings in the brake, permitting
the noise to travel more directly toward the bystander
and shooter. Ports (holes) and slits in the barrel of fire-
arms and muzzle brakes (used to reduce recoil, barrel
elevation, and vibration) are potentially more hazardous
to hearing than firearms without such alterations.
There is also a trend for the unprotected MPEs to
be lower for more powerful hunting rifles than for the
military-style rifles (AR-15, M14, and Tommy gun), par-
ticularly when those rifles were evaluated using the
Coles/CHABA and Smoorenburg DRCs (Fig. 2). The
rationale for this outcome may be that the military-
style firearms have smaller powder capacities (.223,
.308, and .45) than the typical hunting rifles (7 mm
Remington Magnum, .30-06, and .45-70), regardless
of the caliber of the cartridge.
The highest peak noise level from a shotgun at the
bystander location (161.4 dB SPL) was produced by
the largest-gauge shotgun sampled, a 10 gauge firing
a 3.5 inch cartridge. On the other end of the shotgun
noise level range was the .410 gauge shotgun firing
a 3 inch cartridge and producing a peak level of
149.1 dB SPL. When the same 12 gauge shotgun is fired
with two different cartridges (2.75 vs. 3 inch), the longer
cartridge yields a higher peak SPL (150.0 dB), assum-
ing barrel length and distance to the bystander are held
constant. It is also apparent that the larger cartridge
diameters (gauge) yield higher peak SPLs.
The impulse noise from the handgun assessed in this
study should also be mentioned. This small revolver
fired one of the smallest cartridges commercially avail-
able: the .22 Long Rifle. However, the peak was
154.0 dB SPL, which exceeded the peak levels of five
of the other firearms. This may be explained in two
ways. First, the shorter 4 inch barrel length places
the noise source closer to the bystander. Second, since
this firearm is a revolver, there is a significant blast of
gases and noise emitted between the exit chamber from
the cylinder and the rear opening of the barrel, further
reducing the distance between the noise source and the
ears of the bystander. These two factors probably
account for the high SPL for such a small cartridge.
When the Auto-Ordnance .45 Tommy gun and the .22
Ruger revolver noise levels are compared, another
seemingly counterintuitive finding was observed. The
Tommy gun shoots a rather substantial (larger) hand-
gun cartridge (.45 automatic Colt pistol [ACP]) that pro-
duced a peak level of 151.0 dB SPL, while the .22 caliber
Ruger revolver produced a higher peak level (154.0 dB
SPL). This probably again reflects the short barrel
length of the handgun and the opening between the cyl-
inder and barrel when compared to the longer barrel
and closed interface of the chamber with the barrel of
the Tommy gun.
It could be concluded that firing a handgun with a
short barrel length (especially one with a large bore),
compared to long-barreled rifles and shotguns, may
increase the auditory risk factor for the bystander.
And when the handgun is a revolver, the bystander’s
risk for hearing loss may be greater than for semiauto-
matics or single-shot handguns.
Estimates of MPEs were based on the assumption
that the shooter or bystander is unprotected (not wear-
ing earplugs and/or earmuffs). Hearing protectors can
be expected to generally decrease the auditory risks
to the wearer in direct proportion to the reduction in
the peak sound level (W. Murphy, personal communica-
tion, March 4, 2010). Therefore, the unprotected MPEs
from the current study could be adjusted by the propor-
tional effect of a given ear protector. For example, with
Figure 3. Maximum permissible unprotected exposures for each
shotgun and the Ruger .22 caliber handgun, by damage-risk cri-
terion. Error bars represent the range of maximum permissible
unprotected exposures across shots. Separate estimates of maxi-
mum permissible unprotected exposures were obtained for each
cartridge fired in the 12 gauge standard and the .410 caliber shot-
guns. Permissible exposures of 0 returned by the Smoorenburg cri-
terion were entered as 0.1 to permit plotting.
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the Winchester Model 70 (7 mm Remington Magnum)
rifle with the BOSS muzzle brake producing an unpro-
tected MPE of 0.2 (Coles/CHABA DRC) or 4 (Price/Kalb
DRC), an ear protector that reduces the DRCs by a fac-
tor of 100 would increase the MPE to 20 or 400, respec-
tively. Unfortunately, this approach would not be
suitable for the Smoorenburg DRC, because many guns
have an MPE of either 0 or 50 and increases in MPEs
due to the hearing protector would need to be determined
by the effect of the hearing protector on the A-weighted
8 hr equivalent level and the SEL, after transformation
of the recordings under the protector to equivalent levels
in the undisturbed sound field.
None of the guns included in this study should be con-
sidered safe for unprotected bystanders, but the sound
produced by some guns (e.g., Mossberg bolt-action .410)
is less risky than others, and the longer gun barrels and
lower-powered guns and ammunition carry less risk to
the unprotected auditory system. We assumed a graz-
ing incidence for the risk estimates in this study, and
this situation may not always reflect the angle of inci-
dence to the bystander’s ear in the field. The relative
risk of auditory damage may be higher for normal inci-
dence where the acoustic effects of the head and pinna
lead to greater gain in the high frequencies (Shaw,
1974).
The presumed location of the bystander in this study
was 1 m to the left of a right-handed shooter. However,
the sound field surrounding the firearm and shooter is
not uniform (Rasmussen et al, 2009). The results of the
current study can be expected to provide underesti-
mates of sound levels and auditory risk for bystanders
nearer the muzzle (e.g., closer to the shooter or for-
ward) and could overestimate the risk for those farther
away. Companion hunters, shooting instructors, and
long-range precision shooting teams are examples
where bystanders might be closer than the conditions
evaluated in this study. In the case of companion hunt-
ers, particularly waterfowl hunters in a blind, it is pos-
sible to have a group of three or more shooters firing at
flying waterfowl simultaneously from inside an enclo-
sure (e.g., a duck blind [Stewart et al, 2009]). In such
conditions, each person is both a bystander and a
shooter, and each listener’s distance to the muzzle is
determined by the flight path of the bird. Shooting
instructors will occasionally help the student shooter
use the gunsight from a position directly behind the
student shooter. In these conditions, it would be most
appropriate to apply auditory risk estimates obtained
at the shooter’s location. Long-range precision shoot-
ing teams employ a person in the role of spotter who
assists in identifying the location and range to the tar-
get, and competitions of this sort could lead to the spot-
ter occupying a location forward of the shooter,
particularly when shooting from inside an enclosure
or in close quarters.
Clinical Implications
People involved in hearing health care are acutely
aware of the general risk of unprotected firearm noise
exposure for shooters, and this research highlights the
need to extend this clinical awareness to bystanders.
The specific auditory risk to any particular bystander
is contingent upon the shooter’s behavior, the firearm
in use, the number of shots fired, the ammunition used,
and the shooting environment. Bystanders accompany-
ing hunters may not recognize that their relative risk
would be expected to increase when accompanying bird
hunters who may have higher daily limits on quail (10)
and are successful on every third shot versus pheasant
hunters with a lower daily limit (two–five) or deer hunt-
ers who may fire only one or two limited opportunity
shots. Bird hunts are often group hunts, and bystander
exposure is common. Persons functioning as hunting
guides or instructors may find themselves routinely
in the bystander position regardless of the type of hunt-
ing. Many hunters assist other hunters once they have
gained the skills or harvested their personal game, thus
increasing their personal risk of hearing loss.
Hearing protection is advisable for anyone observing
in close proximity to a shooter, whether a family mem-
ber accompanying a hunter to a waterfowl blind or an
observer at a target shooting event. Firearm users who
take turns shooting and become temporary bystanders
may not realize that they could be positioned in a more
hazardous situation than the shooter. These situations
may necessitate the utilization of hearing protection.
Bystanders cannot predict the frequency and acoustic
conditions of impulse noise exposure, and consequently
a conservative approach to universally recommending
HPDs is justified. Shooters themselves may be the most
likely person to advise a bystander of the need to wear
hearing protection, since shooters are often aware of
other safety considerations before firing a shot. Elec-
tronic or nonlinear hearing protection may be especially
useful for bystanders who wish to maintain speech com-
munication and environmental awareness while partic-
ipating in the shooting activity.
It may be advantageous to relocate bystanders or fel-
low shooters to a less hazardous observation point when
feasible and practical. If close observation is not war-
ranted or desired, then increasing the distance between
the bystander and the muzzle blast would be preferable.
In the case of formal shooting events and supervised tar-
get practice,spectators can be required to observe from a
substantial distance. In many sports, video cameras are
used to bring the “action” closer to the spectator, and
these strategies might be useful in terms of hearing loss
prevention for bystanders at shooting events.
Special consideration for children who are bystand-
ers may be warranted, since the World Health Organ-
ization (1999) suggests that children should not be
Auditory Risk to Bystanders/ Flamme et al
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exposed to impulse peak sound levels greater than
120 dB SPL. In this case, hearing protection that fits
well and provides adequate attenuation is necessary
when bystander exposure cannot be avoided. The Amer-
ican culture of passing on hunting traditions from
parents and grandparents to young children can be
respected by counseling adults on the importance of
eliminating unnecessary and unprotected firearm expo-
sure to children and modeling appropriate protective
behaviors.
Audiologists are encouraged to expand their clinical
inquiry beyond asking, “Do you shoot firearms?” to
address any history of firearm noise exposure as a
bystander and/or shooter, e.g., “Are you exposed to
any firearm noise?” Follow-up questions would then
focus on the use of hearing protection, the description
of bystander situations, and the types of firearms (if
known). Any specific occurrences of unprotected firearm
noise exposure should receive special attention. Exten-
sive counseling focusing on higher-risk situations
using high-powered rifles, large shotguns, handguns,
and firearms with muzzle brakes—should emphasize
the need to wear effective HPDs in these instances.
Routine audiologic monitoring should also be encouraged
for bystanders exposed to firearm noise in order to mon-
itor hearing protector effectiveness.
CONCLUSION
Bystanders are at risk of auditory damage from
unprotected civilian firearm noise exposure, and
HPD use is warranted. Civilian firearm impulse noise
peak levels ranged from 149 to 166.5 dB SPL when
measured from a bystander location 1 m to the left of
the shooter. These results illustrate that maximum per-
missible exposures (unprotected) vary across firearms,
ammunition, and DRCs. MPEs ranged from 0 to 217
dependent upon the DRC applied and firearm used.
In general, firearms with longer barrels and lower-
power ammunition are less hazardous to hearing.
The risk of auditory damage is influenced by a variety
of acoustic, firearm, ammunition, environmental, and
circumstantial conditions that cannot always be pre-
dicted in advance of the exposure. Damage-risk criteria
can be used to quantify the relative auditory damage
risk between various firearms and shooting conditions.
Audiologists are advised to consider unprotected
bystander firearm noise exposure in the clinical evalu-
ation of hearing loss and when implementing hearing
loss prevention programs for recreational firearm users
and bystanders/spectators.
Acknowledgments. The authors thank William Murphy
and Edward Zechmann (Centers for Disease Control and Pre-
vention/NIOSH Taft Laboratories) for the MATLAB software
routines used for data analyses and Ed Terrell (G.R.A.S.
Sound and Vibration) for his assistance with this study.
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... Instantaneous peak levels ranged between 149 and 167 dB and were considered to be unsafe exposures for the bystanders. 15 Athletes and spectators near officials firing starter pistols are also at an elevated risk of noise-induced hearing loss (NIHL). 10 The use of electronic starting devices for signaling the start of athletic events may minimize auditory risk. ...
... Escaping gases are ejected closer to the ear and radiate more sound pressure backward toward the shooter, which increases the exposure measured at the shooter's ear. 15 The number of shots fired without hearing protection increases the risk of NIHL. Small game and waterfowl hunters may be at greater risk of NIHL due to shooting hundreds of rounds per season, in comparison to large game hunters who may only fire their rifle a few times during the season. ...
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In the United States and other parts of the world, recreational firearm shooting is a popular sport that puts the hearing of the shooter at risk. Peak sound pressure levels (SPLs) from firearms range from ∼140 to 175 dB. The majority of recreational firearms (excluding small-caliber 0.17 and 0.22 rifles and air rifles) generate between 150 and 165 dB peak SPLs. High-intensity impulse sounds will permanently damage delicate cochlear structures, and thus individuals who shoot firearms are at a higher risk of bilateral, high-frequency, noise-induced hearing loss (NIHL) than peer groups who do not shoot. In this article, we describe several factors that influence the risk of NIHL including the use of a muzzle brake, the number of shots fired, the distance between shooters, the shooting environment, the choice of ammunition, the use of a suppressor, and hearing protection fit and use. Prevention strategies that address these factors and recommendations for specialized hearing protectors designed for shooting sports are offered. Partnerships are needed between the hearing health community, shooting sport groups, and wildlife conservation organizations to develop and disseminate accurate information and promote organizational resources that support hearing loss prevention efforts.
... 43 It is well-established that sounds above 140 dBA can cause permanent hearing damage, and nearly all firearms can surpass this level. 44,45 Consequently, just one round may be sufficient to create noise-induced threshold shifts, 46 contributing to cumulative auditory damage. 44,47,48 Interestingly, we found that over a third (36.6%) of Americans have used a firearm, predominantly in recreational settings, and over 40% of this group have fired over 100 rounds in the past 12 months. ...
... 44,45 Consequently, just one round may be sufficient to create noise-induced threshold shifts, 46 contributing to cumulative auditory damage. 44,47,48 Interestingly, we found that over a third (36.6%) of Americans have used a firearm, predominantly in recreational settings, and over 40% of this group have fired over 100 rounds in the past 12 months. Notably, only 58.5% of those who shot firearms used hearing protection consistently in the last year, whereas the remainder inconsistently or never used hearing protection. ...
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... The overall highest single pressure reading occurred in P SV during one laser pulse on the footplate (>10 kPa), whereas the highest estimated EAC pressure was in P ST during stapes downfracture (>170 dB SPL peak). These SPL values are comparable in intensity to firearm discharge (28), and thereby have the potential to cause significant damage to the auditory and vestibular end organs. Notably, the Occupational Safety and Health Administration (OSHA) standard for occupational noise exposure states that impulse noise should not exceed 140 dB SPL peak, suggesting nearly every procedure conducted during stapedotomy surgery (especially those involving lasering) has the potential to generate unsafe noise levels in the human ear (21). ...
Article
Hypothesis: Surgical manipulations during laser stapedotomy can produce intracochlear pressure changes comparable to pressures created by high-intensity acoustic stimuli. Background: New-onset sensorineural hearing loss is a known risk of stapes surgery and may result from pressure changes from laser use or other surgical manipulations. Here, we test the hypothesis that high sound pressure levels are generated in the cochlea during laser stapedotomy. Methods: Human cadaveric heads underwent mastoidectomy. Fiber-optic sensors were placed in scala tympani and vestibuli to measure intracochlear pressures during key steps in stapedotomy surgery, including cutting stapedius tendon, lasering of stapedial crurae, crural downfracture, and lasering of the footplate. Results: Key steps in laser stapedotomy produced high-intensity pressures in the cochlea. Pressure transients were comparable to intracochlear pressures measured in response to high intensity impulsive acoustic stimuli. Conclusion: Our results demonstrate that surgical manipulations during laser stapedotomy can create significant pressure changes within the cochlea, suggesting laser application should be minimized and alternatives to mechanical downfracture should be investigated. Results from this investigation suggest that intracochlear pressure transients from stapedotomy may be of sufficient magnitude to cause damage to the sensory epithelium and affirm the importance of limiting surgical traumatic exposures.
... These values substantially exceed the maximum permissible noise level (5). Exposure to firearms noise causes a sensorineural type hearing loss (6,7). Dogs with conductive hearing disorder can be successfully treated medically and surgically, and hearing may be regained in some cases. ...
Article
This study investigates the possibility of acoustic trauma occurence in hunting dogs exposed to high noise with pure stimulant such as firearms. Ten puppies (Control Group-CG) were used to establish reference for Brainstem Auditory Evoked Response (BAER) and tympanometry records. BAER and tympanograms were collected from the 40 cases in active hunting group (Acoustic Trauma Group-ATG). The severities of trauma of which the cases were exposed to were determined by field study. While tympanometric pressure values of ATG cases were higher than that in CG, they were found to be in normal range (ATG left: 35,63±38,79/right: 34,00±38,25; CG left:-23,90±44,30/ right:-29,20±36,87 daPa). BAER records were saved using both click and tone burst stimuli. Records were taken at the frequencies of 0,5, 1, 2, 4, 6, 8-kHz with tone burst stimulus. Wave I latency values obtained with click stimulus were only found to be significant in right ear at 30 dB intensity. Wave V was observed to be the last disappearing and the most observed wave among the waves obtained with high frequency stimulus. Based on this study, it was concluded that dogs experience acoustic trauma due to firearm noise, as revealed by a substantial decline in amplitude values in BAER records obtained with click stimulus. It can be said that the use of products developed for dogs and raising awareness in hunters may also be beneficial to prevent harmful effects of acoustic trauma. Av köpeklerinde ateşli silah gürültüsü ile akustik travma olur mu? 50 av köpeğinde prospektif bir çalışma Özet: Bu çalışmada, ateşli silahlar gibi saf uyaranlı yüksek şiddetli gürültüye maruz kalan av köpeklerinde akustik travma olup olmadığının araştırılması amaçlandı. Referans Beyin Sapı İşitsel Uyandırılmış Yanıtları (BAER) ve timpanometri kayıtlarını oluşturmak için 10 av köpeği (Kontrol Grubu-CG) kullanıldı. 40 olgudan oluşan aktif av grubundan (Akustik Travma Grubu-ATG) BAER ve timpanogramlar alındı. Olguların maruz kaldığı travmanın şiddeti saha çalışması ile belirlendi. ATG olgularının timpanometrik basınç değerleri CG'deki değerlerden daha yüksek iken (ATG left: 35,63 ± 38,79 / right: 34,00 ± 38,25; CG left-23,90 ± 44,30 / right:-29,20 ± 36,87 DaPa) BAER kayıtları hem klik hem de tone burst uyaranları kullanılarak kaydedildi. Kayıtlar, tone burst uyarı ile 0,5, 1, 2, 4, 6, 8-kHz frekanslarında alındı. Klik uyaranı ile elde edilen Dalga I gecikme değerlerinin sağ kulakta 30 dB yoğunlukta anlamlı olduğu bulundu. Dalga V, yüksek frekans uyarısı ile elde edilen dalgalar arasında en son kaybolan ve en çok gözlenen dalga olarak gözlendi. Bu çalışma ile ateşli silah gürültüsüne bağlı akustik travmanın köpeklerde klik uyaranla elde edilen BAER kayıtlarında amplitüd değerlerindeki belirgin düşüşle ortaya konulabileceği sonucuna varıldı. Akustik travmanın zararlı etkilerinden korunmak için avcıların bilinçlendirilmesi ile köpekler için geliştirilen ürünlerin kullanımının da faydalı olabileceği söylenebilir.
... This risk is not limited to the firearm user. Recent research has indicated that firearm noise exposure can be hazardous on hearing for the shooter and nearby bystanders ( Flamme et al. 2011). In addition to hearing loss, tinnitus can also develop as a result of firearm exposure. ...
Article
To determine if conventional audiometry, EHFA, and pDPOAEs are useful as early indicators of cochlear damage from recreational firearm impulse noise exposure in youth firearm users. Quantitative cross-sectional descriptive pilot study. Descriptive statistics and MANOVA with post hoc Tukey Honestly Significant Difference test were used to compare pDPOAEs (1–10 kHz), conventional audiometry (0.25–8 kHz), and EHFA (10–16 kHz) in YFUs. 25 YFUs (n = 11 7–12 years; n = 14 13–17 years) with self-reported poor compliance with hearing protector device wear. Conventional audiometric thresholds at 2-, 3- and 4 kHz were significantly poorer than normal but did not distinguish between older and younger YFUs or between the GBE and the contralateral ear. EHFA thresholds at 14- and 16 kHz were significantly poorer than for other frequencies, and differentiate between older and younger youths, but do not distinguish the GBE from the contralateral ear. Finally, pDPOAE levels were significantly reduced at 8- and 10 kHz but did not show any differences for the younger versus older YFUs or for the GBE from the contralateral ear. Conclusion: Both EHFA and pDPOAEs provide early evidence of NIHL in YFUs, and may be useful for the early detection of NIHL in YFUs. © 2019, © 2019 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society.
... These values substantially exceed the maximum permissible noise level (5). Exposure to firearms noise causes a sensorineural type hearing loss (6,7). Dogs with conductive hearing disorder can be successfully treated medically and surgically, and hearing may be regained in some cases. ...
Article
Full-text available
This study investigates the possibility of acoustic trauma occurence in hunting dogs exposed to high noise with pure stimulant such as firearms. Ten puppies (Control Group-CG) were used to establish reference for Brainstem Auditory Evoked Response (BAER) and tympanometry records. BAER and tympanograms were collected from the 40 cases in active hunting group (Acoustic Trauma Group-ATG). The severities of trauma of which the cases were exposed to were determined by field study. While tympanometric pressure values of ATG cases were higher than that in CG, they were found to be in normal range (ATG left: 35,63±38,79/right: 34,00±38,25; CG left:-23,90±44,30/ right:-29,20±36,87 daPa). BAER records were saved using both click and tone burst stimuli. Records were taken at the frequencies of 0,5, 1, 2, 4, 6, 8-kHz with tone burst stimulus. Wave I latency values obtained with click stimulus were only found to be significant in right ear at 30 dB intensity. Wave V was observed to be the last disappearing and the most observed wave among the waves obtained with high frequency stimulus. Based on this study, it was concluded that dogs experience acoustic trauma due to firearm noise, as revealed by a substantial decline in amplitude values in BAER records obtained with click stimulus. It can be said that the use of products developed for dogs and raising awareness in hunters may also be beneficial to prevent harmful effects of acoustic trauma. © 2018, Chartered Inst. of Building Services Engineers. All rights reserved.
... A growing body of evidence suggests that the number of individuals exposed to impulse noise is markedly higher than previously supposed. Flamme et al. [23] analyzed the risk of hearing loss resulting from exposure to firearm noise among bystanders (friends, spouses and children), who are often present during hunting and recreational shooting activities and frequently underestimate the hazard posed by the noise. It is noteworthy that exposure to noise generated during blasting testing was not limited solely to individuals directly involved in the tests, but included also nearly 500 other employees of the explosives company and local residents. ...
Article
Impulse noise encountered in workplaces is a threat to hearing. The aim of this study was to assess the occupational exposure to impulse noise produced by detonation of dynamite in the premises of an explosives company. Test points were located on the blast test area (inside and outside the bunker) and in work buildings across the site. Noise propagation measurement was performed during 130 blast tests in 9 measurement points. At every point, at least 10 separate measurements of equivalent A-weighted sound pressure levels (LAeq), maximum A-weighted sound pressure level (LAmax), and C-weighted peak sound pressure level (LCpeak) were made. Noise recorded in the blast test area exceeded occupational exposure limits (OELs). Noise levels measured in buildings did not exceed the OELs. Results of the survey showed that for 62% of respondents, impulse noise causes difficulties in performing work. The most commonly reported symptoms include headaches, nervousness and irritability.
... Many large bore firearms that generate peak noise levels above 160 dB peak SPL at the shooters' ear, closest to the muzzle, result in maximum permissible exposures (MPEs) of less than one shot when applying an A-weighted 8-hour equivalent energy level, LAeq8, and a limit of 85 dBA . Flamme et al., (2011) employed three different damage risk criteria (DRC) and also calculated MPEs of one or less for a variety of large bore rifles and shotguns at the bystander position (1 meter behind the shooter). In addition, some air rifles have been found to exceed the 120 dB peak SPL limit for children (Lankford et al., 2016). ...
Article
Full-text available
Recreational firearm use is a popular leisure-time activity in the United States today. Millions of Americans of all ages enjoy shooting sports including target practice, competitive shooting, and hunting. While participation in the shooting sports can be an enjoyable recreational pursuit, it can also put an individual at risk for noise-induced hearing loss (NIHL) and tinnitus resulting from unprotected exposure to high-intensity firearm noise. Almost all firearms generate impulse levels in excess of 140 dB peak SPL. Hearing loss may occur gradually over time due to repeated unprotected exposure to firearm noise. Hearing loss also may occur suddenly due to acoustic trauma from a single unprotected gunshot. The hearing loss is often characterized by normal or near normal hearing sensitivity in the lower frequency range with severely impaired hearing in the higher frequency range which results in difficulty hearing speech clearly. NHCA developed this guidance document to assist hearing conservationists, audiologists, physicians and other hearing conservation professionals, in managing and mitigating the risk of NIHL associated with recreational firearm noise. Several strategies can be employed to reduce the risk of acquiring NIHL and associated tinnitus from firearm noise exposure. These include wearing hearing protection devices (HPDs), using firearms equipped with suppressors, choosing smaller caliber firearms, using subsonic ammunition, shooting in a non-reverberant environment, and avoiding shooting in groups. In addition, several commercially-available HPDs are specifically designed for the shooting sports. These include conventional passive earmuffs and earplugs, level-dependent devices that attenuate high level sound while providing audibility for lower level sound, and electronic devices that amplify low level sounds and attenuate high level hazardous sounds. The key to preventing NIHL and tinnitus secondary to excessive firearm noise exposure is to educate firearm users about the auditory hazard associated with firearm noise and provide them with strategies to protect their hearing. Educational programs may be offered through hunter safety courses, hunting clubs, or during training. A special firearm noise topic section should be included in occupational educational training for individuals who use firearms as part of their jobs. Finally, clinical audiologists should educate their patients who use firearms regarding the hazards and ways to prevent hearing loss. Several educational tools are available on the National Hearing Conservation Association website including a hearing loss simulator, a tinnitus simulator, posters and slides of inner ear structures damaged by firearm noise, a hearing protection brochure, a hunting and hearing video and links to other educational resources. Firearm NIHL is almost completely preventable if necessary precautions are taken.
Article
Firearms produce peak sound pressure levels (peak SPL) between ∼130 and 175 dB peak SPL, creating significant risk of noise-induced hearing loss (NIHL) in those exposed to firearm noise during occupational, recreational, and/or military operations. Noise-induced tinnitus and hearing loss are common in military service members, public safety officers, and hunters/shooters. Given the significant risk of NIHL due to firearm and other noise sources, there is an interest in, and demand for, interventions to prevent and/or treat NIHL in high-risk populations. However, research and clinical trial designs assessing NIHL prevention have varied due to inconsistent data from the literature, specifically with end point definitions, study protocols, and assessment methodologies. This article presents a scoping review of the literature pertaining to auditory changes following firearm noise exposure. Meta-analysis was not possible due to heterogeneity of the study designs. Recommendations regarding audiologic test approach and monitoring of populations at risk for NIHL are presented based on critical review of the existing literature.
Article
Purpose Noise-induced hearing loss (NIHL) has been found in rural children, potentially due to occupational and recreational noise exposure without consistent use of hearing protection devices (HPDs). However, questions remain regarding the specifics of rural adolescents' noise exposure and use of hearing protection around different types of noise. As such, the purpose of the current study was to provide preliminary results on rural adolescents' noise exposure and use of hearing protection for gunfire, heavy machinery, power tools, all-terrain vehicles (ATVs), and music. Method A questionnaire was administered to 197 students (seventh to 12th grade) from rural schools in West Texas. Questions were related to noise exposure and use of HPDs for specific categories of noise. Testing was performed at the schools, with an investigator recording each student's responses. Results Approximately 18%–44% of adolescents reported exposure 12 or more times a year to gunfire, heavy machinery, power tools, and ATVs. Only 1%–18% of the adolescents reported never being exposed to such noise sources. Almost half of rural adolescents never used hearing protection around gunfire, and 77%–91% reported never wearing hearing protection when exposed to heavy machinery, power tools, and ATVs. Conclusions The current study revealed that rural adolescents are exposed to noise sources that could damage their hearing. However, the majority of rural adolescents do not consistently wear hearing protection. Additional research is now needed to extend these findings by assessing rural adolescents' duration of exposure to different noise sources, in addition to investigating prevention of NIHL in this population. Supplemental Material https://doi.org/10.23641/asha.17139335
Chapter
The instrumentation used for measuring noise may range from a simple sound-level meter to a sophisticated signal analysis processing system.
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This paper presents impulse‐noise damage‐risk criteria based on conclusions of independent British and American studies and on the work of other research workers in this field. Most of the studies that led to this criterion were performed with noise from small arms, but the criterion is general enough to permit assessment of most other types of impulse noise. The variables that must be considered in determining the potential hearing hazard and in the practical application of the criteria are presented, and the parameters that must be measured are defined. The measurement technique and type of transducers to be used are discussed.
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This important document replaces the 1980 Environmental Health Criteria No.12 – Noise. It is destined to become widely used and quoted in relation to environmental noise problems. All who have even a passing involvement in this area must become familiar with it and with its recommended levels. The Report considers noise sources and their measurement, adverse effects on health and noise management, whilst introducing a new set of recommendations and guideline values to take account of changes in knowledge and expectations over the past 20 years. Attention is drawn to inadequacies of equivalent level for intermittent noises, to the need to consider effects of low frequency noise and to the rights of vulnerable sub-groups. The Guide can be viewed in full on the World Health Organisation website – www.who.org
Article
OBJECTIVE: To assess the relation between recreational firearm use and high-frequency hearing loss in a population of older adults. DESIGN: Cross-sectional, population-based cohort study. SETTING: The midwestern community of Beaver Dam, Wis. PARTICIPANTS: A population-based sample of 3753 participants (83% of those eligible), aged 48 to 92 years, participated in the baseline phase of the Epidemiology of Hearing Loss Study. INTERVENTION: None. MAIN OUTCOME MEASURES: Lifetime and past year self-reported firearm use during target shooting and hunting were assessed by interview. Hearing thresholds were measured by pure-tone audiometry. RESULTS: After age and other factors were adjusted for, men (n = 1538) who had ever regularly engaged in target shooting (odds ratio, 1.57; 95% confidence interval, 1.12-2.19) or who had done so in the past year (odds ratio, 2.00; 95% confidence interval, 1.15-3.46) were more likely to have a marked high-frequency hearing loss than those who had not. Risk of having a marked high-frequency hearing loss increased 7% for every 5 years the men had hunted (odds ratio, 1.07; 95% confidence interval, 1.03-1.12). Thirty-eight percent of the target shooters and 95% of the hunters reported never wearing hearing protection while shooting in the past year. CONCLUSIONS: These results indicate that use of recreational firearms is associated with marked high-frequency hearing loss in men. There is a need for further education of users of recreational firearms regarding the risk of hearing impairment associated with firearm use and the availability and importance of appropriate hearing protection.
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This report is intended to complement the National and State Reports for the
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The energy spectrum of a noise is known to be an important effects of a traumatic exposure. However, existing criteria for exposure to impulse noise do not consider the frequency spectrum of an impulse as a variable in the evaluation of the hazards to the auditory system. This report presents the results of three studies that were designed to determine the relative potential that impulsive energy has in causing auditory system trauma. Four hundred and seventy five (475) chinchilla were used in these experiments. Pre- and post- exposure hearing thresholds were measured on each subject. In the first study, the noise exposure stimuli consisted of six different computer-generated narrow band tone bursts having center frequencies located at 0.260, 0.775, 1.025, 1. 350, 2.450, and 3.550 kHz. Each narrow band exposure stimulus was presented at two to four different intensities. An analysis of the audiometric data allowed a frequency weighting function to be derived. This weighting function de- emphasizes low frequency energy more than the conventional A-weighting function. In the second study, the exposures consisted of two--types of broad band computer synthesized impulses. Subjects were exposed to 100 impulses at a rate of 1-per-3-seconds. Each type of impulse was presented at 3 intensities. The third study used impulses generated by three different diameter shock tubes. Subjects were exposed to 1, 10, or 100 impulses at one of three intensities. The results of the second and third studies were interpreted using the weighting' function derived from the first study. The hearing loss from all three studies is a linear function of the weighted SEL calculated using the weighting function, derived in the first study. Impulse noise, Hearing, Chinchilla, Audiometry and histology.
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Criteria are presented for assessing damage risk from impulse-noise exposure. The criteria are based on conclusions of independent British and American studies and on the work of other research workers in this field. Most of the studies which led to these criteria were performed with noise from small arms, but the criteria are general enough to permit assessment of most other types of impulse noise. The variables which must be considered in determining the potential hearing hazard and in making practical application of the criteria are presented, and the parameters which must be measured are defined. The measurement technique and type of transducers to be used are discussed.
Article
Des recherches sur l'élévation du seuil auditif du au bruit d'armes légères ont prouvées: (1) de grandes différences individuelles de susceptibilité pour ce genre de bruit; (2) une forte corrélation entre l'élévation temporaire du seuil et l'apparition du tintement; (3) la valeur de l'utilisation d'un seul chiffre (la moyenne des élévations maximales de tous les sujets) pour représenter en groupes l'élévation du seuil. (4) des protecteurs d'oreille avec une atténuation de plus de 30 dB suffisent pour prévenir l'élévation du seuil. Le mesurage du bruit émis par des armes légéres ont demontré que la somme des niveaux de pression acoustique se situe à environ 160 dB, près de l'oreille du tireur. Le spectre est à peu près égal pour tous les fréquences perceptibles au dessus de 1000 Hz. En arrière de l'arme, les niveaux de pression acoustique sont moins hauts que dans les autres directions.