September-October 2012 | Volume 14 | Issue 60
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MEDLINE, EMBASE & SCI
A Bi-monthly Inter-disciplinary International Journal
Noise & Health, September-October 2012, Volume 14:60, 224-6
The pet industry in the United States is robust and expanding
with an estimated 78.2 million dogs in 46.3 million homes in
2010 and yearly profits of 48.35 billion dollars, 2.9 billion
dollars of which was spent on grooming. It is estimated that
there are 60,000-80,000 professional groomers in the United
States. One of the primary tools of the dog grooming trade
is the forced-air dryer, also known as high-velocity dryers.
Our survey of groomers showed that a typical professional
groomer or groomer/bather is exposed to the source level
of these forced-air dryers for an average of two hours per
day, totaling about ten hours per week. The highest levels of
exposure were about twice that, totaling as much as twenty
hours per week.
Most noise exposures in the US occur in the mining,
manufacturing, and construction industries. A much smaller
percentage of noise exposures are reported in the Services
sector. However, there are instances of high noise exposures
within service-oriented occupations. Unfortunately, workers
in businesses that are not typically known for having high
workplace noise exposures are much less likely to wear
hearing protection than workers in traditionally noisy jobs.
Much of the existing literature on noise levels in animal
care facilities pertains to the adverse effects of noise on the
psychological well-being of the dogs.[4,5]Anecdotal evidence
from groomer trade publications and websites suggests that
the noise produced by forced-air dryers causes many dogs to
be frightened. However, little research has been conducted
on hazardous noise levels in animal-related facilities with
respect to its effect on human hearing. This study was
conducted to measure and quantify the extent of the hazard
posed for dog groomers when using forced-air dryers. The
authors are also very much interested in the effects of noise
on dogs, but this issue was not addressed in this study since
dryer exposure for dogs themselves is likely very limited as
compared to groomers.
Four of the most commonly used forced-air dryers that were
tested for this investigation are listed in Table 1. Typically,
when these dryers are being used the positions of the groomer
and the dog being groomed are within 1 meter of the source,
and thus both are exposed to significant noise levels from
the equipment. In this study, we investigated four dryers
of different makes and models used in typical grooming
Noise impacts from professional dog grooming
Peter M. Scheifele, Michael T. Johnson1, David C. Byrne2, John G. Clark,
Ashley Vandlik, Laura W. Kretschmer, Kristine E. Sonstrom
Communication Sciences and Disorders Department, University of Cincinnati, 1Department of Electrical and Computer Engineering,
Marquette University, 2National Institute for Occupational Safety and Health, Cincinnati, Ohio, USA
This study was designed to measure the sound output of four commonly used brands of forced-air dryers used by dog
groomers in the United States. Many dog groomers have questions about the effect of this exposure on their hearing, as
well as on the hearing of the dogs that are being groomed. Readings taken from each dryer at 1 meter (the likely distance of
the dryer from the groomer and the dog) showed average levels ranging from 105.5 to 108.3 dB SPL or 94.8 to 108.0 dBA.
Using the 90 dBA criterion required by the US Occupational Safety and Health Administration, dog groomers/bathers are
at risk if exposure to the lowest intensity dryer (94.8 dBA) exceeds 4 hours per day. If the more stringent 85 dBA criterion
and 3 dB tradeoff is applied, less than one hour of exposure is permissible in an 8 hour day. Cautions are recommended for
any persons exposed to noise from forced-air dryers.
Keywords: Dryer noise, Hearing protection, Service occupations
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Scheifele, et al.: Noise impacts: Dog grooming forced-air dryers
Noise & Health, September-October 2012, Volume 14
situations to determine source levels and exposure of both
the groomer and dog being groomed.
Noise level measurements were taken using a Bruel and
Kjaer Type 2270 sound level meter with ½-inch Type 4189
microphone using BZ-7223 frequency analysis software. This
sound level meter was calibrated using a Bruel and Kjaer
Type 4231 sound calibrator. The microphone was positioned
between the dog and groomer and the dryer nozzle. Each dryer
was measured under typical operating conditions for 5 minutes
to obtain a representative Leq (average) noise sample.
Both a one-third octave-band analysis based on ISO standard
R 266 and ANSI S1.6-1984 and a high resolution power
spectrum analysis were used to quantify the sound levels
within the hearing range of the human groomer and dog
being groomed.[6-8] The high resolution power spectrum
is a representation of sound pressure level as a function of
frequency in kilohertz (kHz). Spectral analyses of acoustic
recordings were accomplished through averaging the fourier
transform of the signal across multiple one-second windows,
using the Matlab Signal Processing Toolbox. In addition,
the average overall sound pressure level in dB SPL and
A-weighted sound pressure level in dBA were computed from
the recorded signal and the microphone sensitivity values.
Recordings for power spectral analysis were taken using an
M-Audio Microtrack II™ recorder with cardioid condenser
microphone. All calibrations were relative to a 1000 Hz tone
at 94 dB ± 0.2 dB. The microphone sensitivity was -58 dB re
1V/Pa ± 2.5 dB where 1 Pa = 94 dB SPL. Recordings were
made in one-minute segments during the dryer operation.
All dryers showed elevated noise levels in the bands between
400 Hz and 10 kHz. The average sound levels in dB SPL and
dBA for the four makes of dryers is shown in Table 2.
All four of the dryers tested show significant noise levels that
have the potential to impact groomer and animal hearing.
While overall sound pressure levels are somewhat similar
across the four models, there are some differences in the
frequency characteristics. The K9 II, Metro Air Force Master
Blaster, and MDC Romani Granddaddy models all exhibit
similar sound levels in the human hearing range, with overall
noise levels of 105-108dBA and almost all noise power in
that range so that dB SPL and dBA are nearly identical. In
contrast, the double K Challenge Air DBL9000 II model
has similar overall noise power but differing frequency
characteristics, including significant energy in the 0-20Hz
range, so that the A-weighted noise level is somewhat lower,
In the US, the Occupational Safety and Health Administration
(OSHA) standard for occupational noise exposure specifies a
limit of 90 dBA for an 8-hour workday, using a 5 dB exchange
rate (time/intensity trading relationship). While the US
OSHA standards have the legal backing of federal regulation,
the US National Institute for Occupational Safety and Health
(NIOSH) has recommended more stringent guidelines that
include a more protective 3 dB time-intensity tradeoff.
This latter guideline is becoming the benchmark for standard
of care by many hearing conservation professionals. Using
either guideline, the dryer noise levels that dog groomers
may be exposed to is excessive and puts their hearing at risk.
Given the significantly greater amount of time groomers
are exposed to the sound of the dryers, groomer risk far
exceeds that of their canine patrons. Indeed the dog exposure
is both more limited and infrequent and as such may be
To be specific, the average sound level for three of the
four makes of dryer in this study was 105-108 dBA.
OSHA regulations limit exposure to this level of noise to
40-60 minutes per workday. The more stringent NIOSH
guidelines would limit exposure to less than five minutes
within an 8 hour work day. Yet according to our survey, a
professional groomer is exposed to the source level of these
forced-air dryers for two hours per day with the potential
for professional groomers’ exposure reaching as much as
four hours per day. Using the lowest (i.e., 94.8dBA) noise-
producing dryer would allow a groomer to operate for
approximately four hours under the OSHA regulation and
47 minutes using the NIOSH recommended limits.
Conclusions and recommendations
Noise level measurements of the four dryers investigated in
this study clearly exceed allowable and safe levels given the
reported lengths of time a groomer may be working with the
Table 1: Specifications for professional dog grooming forced-air
Max air flow
Air force master blaster
Challenge air DBL9000
II stand dryer
MDC Romani, Inc. Granddaddy24856,000
Table 2: Average sound pressure levels for forced-air dryers
MetroAir force master blaster
Double KChallenge air DBL9000 II stand
MDC Romani, Inc. Granddaddy
Scheifele, et al.: Noise impacts: Dog grooming forced-air dryers Download full-text
Noise & Health, September-October 2012, Volume 14
dryers in a given day. The hearing health of dog groomers
who use these commonly employed dryers is at risk. Hearing
protection as used in any high noise employment setting
should be standard for dog groomers exposed to dryer noise
for more than one hour to be in compliance with regulations
set by the Occupational Health and Safety Administration.
Use of hearing protection for shorter exposure times is
recommended and would be in agreement with guidelines
developed by the National Institute for Occupational Safety
and Health. Dogs are not considered to be at imminent risk
of hearing damage from dryer noise given the minimal time
of exposure that occurs on an infrequent basis. However,
groomers have noted that dogs may be easier to handle
during the grooming process if their ears are covered while
dryers are on.
Address for correspondence:
Dr. Peter M. Scheifele,
Colleges of Allied Health Sciences and Medicine,
Communication Sciences and Disorders Department and
Department of Medical Education, 345A French East Bldg,
3202 Eden Ave, Cincinnati, OH 45267-0379, USA.
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How to cite this article: Scheifele PM, Johnson MT, Byrne DC,
Clark JG, Vandlik A, Kretschmer LW, et al. Noise impacts from
professional dog grooming forced-air dryers. Noise Health 2012;14:224-6.
Source of Support: Nil, Conflict of Interest: None declared.
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