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Download by: [University of California, San Diego] Date: 12 January 2016, At: 03:05
Journal of Occupational and Environmental Hygiene
ISSN: 1545-9624 (Print) 1545-9632 (Online) Journal homepage: http://www.tandfonline.com/loi/uoeh20
Evaluation of mobile smartphones app as a
screening tool for environmental noise monitoring
Titus S. Ibekwe, David O. Folorunsho, Enoch A. Dahilo, Ibeneche O. Gbujie,
Maxwell M. Nwegbu & Onyekwere G. Nwaorgu
To cite this article: Titus S. Ibekwe, David O. Folorunsho, Enoch A. Dahilo, Ibeneche O. Gbujie,
Maxwell M. Nwegbu & Onyekwere G. Nwaorgu (2016) Evaluation of mobile smartphones
app as a screening tool for environmental noise monitoring, Journal of Occupational and
Environmental Hygiene, 13:2, D31-D36, DOI: 10.1080/15459624.2015.1093134
To link to this article: http://dx.doi.org/10.1080/15459624.2015.1093134
Accepted author version posted online: 29
Sep 2015.
Published online: 08 Jan 2016.
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JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE
, VOL. , NO. , D–D
http://dx.doi.org/./..
Case Study
Column Editor: James McGlothlin
Evaluation of mobile smartphones app as a screening tool for
environmental noise monitoring
Reported By
Titus S. Ibekwea,b, David O. Folorunshoa, Enoch A. Dahiloa,b, Ibeneche O. Gbujiea, Maxwell M. Nwegbub,c,and
Onyekwere G. Nwaorgud
aDepartment of ENT, University of Abuja Teaching Hospital, Abuja, Nigeria; bCollege of Health Sciences, University of Abuja, Nigeria;
cDepartment of Chemical Pathology, University of Abuja Teaching Hospital, Abuja, Nigeria; dDepartment of Otolaryngology, University College
Hospital Ibadan & College of Medicine, University of Ibadan, Nigeria
KEYWORDS
Androidboy “app”; noise;
noise measuring device;
smartphones; sound level
meter
ABSTRACT
Noise is a global occupational and environmental health hazard with considerable social and phys-
iological impact and, therefore, there is a need for regular measurements to boost monitoring and
regulations of environmental noise levels in our communities. This necessitates a readily available,
inexpensive, and easy to use noise measuring device. We aimed to test the sensitivity and validity of
mobile “smart” phones for this purpose.
This was a comparative analysis of a cross sectional study done between January 2014 and February
2015. Noise levels were measured simultaneously at dierent locations within Abuja Nigeria at day and
night hours in real time environments. A sound level meter (SLM) (Extech407730 Digital Soundmeter,
serial no.: 2310135, calibration no: 91037) and three smartphones (Samsung Galaxy note3, Nokia S, and
Techno Phantom Z running on Android “Apps”Androidboy1) were used. Statistical calculations were
done with Pearson correlation, T-test and Consistency within American National Standards Institute
acceptable standard errors.
Noise level readings for both daytime and night with the SLM and the mobile phones showed equiva-
lent values. All noise level meters measured were <100dB. The daytime readings were nearly identical
in six locations and the maximum dierence in values between the SLM and Smartphone instruments
was 3db, noted in two locations. Readings in dBA showed strong correlation (r =0.9) within accept-
able error limits for Type 2 SLM devices and no signicant dierence in the values (p =0.12 & 0.58) for
both day and night. Sensitivity of the instrument yielded 92.9%.
The androidboy1 “app” performance in this study showed a good correlation and comparative high
sensitivity to the Standard SLM (type 2 SLM device). However there is the need for further studies.
Introduction
Noise is a global occupational health hazard with con-
siderable social and physiological impact.[1] Noise is fre-
quently described as an unwanted or unpleasant sound
or an intense sound capable of damaging the inner ear.[2]
Environmental noise is the summary of noise pollution
from outside, caused by transport, industrial, domestic,
and recreational activities. Sustained exposure to loud
noise has other adverse consequences besides hearing
CONTACT Titus S. Ibekwe ibekwets@yahoo.com Department of ENT,College of Health Sciences University of Abuja & University of Abuja Teaching Hospital,
Abuja, Nigeria.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/uoeh.
loss such as elevated blood pressure, sleeping dicul-
ties, annoyance, and stress which have been extensively
reported in the literature.[2,4] Unfortunately, increased
activities from industrialization has been accompanied by
worsening noise pollution in most fast growing cities and
hence the need for concerted eort in monitoring and reg-
ulating environmental noise levels in our communities.
Dierent instruments are used to measure noise levels
which include, the noise dosimeter, the integrating sound
level meter (ISLM) and the sound level meter (SLM).
© JOEH, LLC
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D32 T. S. IBEKWE ET AL.
A noise dosimeter is a portable, light device worn on
the body with a microphone attached to the collar of the
clothes. It stores information on noise level and records
the average noise level.[3] The bearer goes around with the
device while working, especially for industry workers, and
it takes record of noise levels at dierent locations.
The integrating sound level meter has similar features
andfunctionsasthedosimeter,butcanbehand-held,and
takesmeasurementataparticularlocation.Itisworthy
of note that unlike the former it gives single value read-
ing for any given location. The Sound Level Meter (SLM)
has a basic arrangement which comprises a microphone,
aprocessingsection,andaread-outunit(Figure 1). The
measurement is carried out by aiming the meter’s micro-
phone toward the sound source, at a distance of about one
meter (1 m), or an arm’s length at the ear height and at
a90°angle to the direction of the sound. However, for
most SLMs the pattern of positioning of the microphone
towardsthenoisesourceisoflittleconsequence.There
are two main forms or types of SLMs: Type 1 and 2. Type 1
SLM is used for highly precise engineering, laborator y and
research work, while Type 2 SLM is for industrial and eld
evaluations.Type2SLMthoughlesssensitivethanType1,
meetstheOccupationalSafetyandHealthAdministration
(OSHA)’s set occupational/environmental noise monitor-
ing requirements[5] and therefore is commonly deployed
for environmental and eld noise monitoring. Most SLMs
belong to this latter class.
A recent breakthrough in mobile phone technology is
application of sound level measurement in smartphones.
The inclusion of these applications (“apps”) within these
phones carries a number of advantages; widespread avail-
ability (the mobile subscriptions by the year 2014 had
reached the 6.8 billion mark and about 65% of all mobile
phones sold in 2014 were smartphones),[6] ease of use,
portability and low cost. It can be easily utilized as “Type
2 SLM” community-oriented monitoring equipment for
noise control by all, especially in sectors such as the indus-
trial workplace/setting wherein workers can assess the
noise level on their own without relying on their employ-
ers to undertake such for them. However this can only be
possible if the accuracy of SLM “apps” is within accept-
able standard, hence the need for this work. According
to the American Association National Standard Institute
of Audiolology (ANSI), the acceptable error margins for
values emanating from SLM instruments are as follows:
±1dBA for Type 1 instruments and ±2dBA for Type 2
instruments.[7,8] It is worthy of note that some school of
thought consider 3 to 5dBA dierence as signicant for
Type 2 instrument within real time and uncensored envi-
ronment considering the premium placed on these values
by NIOSH and OSHA.[9,10] They proered that increment
by 3 dBA and 5 dBA, respectively, in perceived sounds by
unaided ear is equivalent to halving the safe listening time.
Figure . Type Sound level Meter (SLM) Extech Model.
To the best of our knowledge, there is no data concern-
ing the use and accuracy of SLMs in mobile/smartphones
in Africa and this is not surprising since the global data is
just emerging[11–13] and as such this study is set to assess
the validity and sensitivity of this simple tool compared to
the standard sound level meter measurements in real time
and uncensored environment. Findings from our study
will contribute to the body of knowledge to further noise
evaluations in other parts of Africa for the utility of this
ubiquitous tool.
Objective
Totestthesensitivityandvalidityofmobilephonesas
noise measuring devices compared to standard sound
level meters.
Methods
This is a comparative analysis of a cross sectional study
carried out between January 2014 and February 2015.
Noise levels were measured at dierent locations within
AbujatheFederalCapitalTerritory(FCT)ofNigeria
at day hours (9 am–noon) and night hours (9 pm–12
midnight) in real time and uncensored environments. A
sound level meter (Extech 407730 Digital Sound Level
Meter, Nashua, New Hampshire, USA) (see Figure 1)and
three smartphones (Samsung Galaxy note 3; Nokia S; and
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JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE D33
Figure . Sound level meters of the three different android phones.
Tecno Phantom Z running on Android “Apps” Android-
boy1)(seeFigure 2)wereusedforthemeasurementsof
the environmental sound levels (dBA). The SLM was cal-
ibrated in January 2014. The mobile phone sound level
application (“apps”) was chosen based on a superior com-
parative performance and rating against other common
android SLM “Apps” using the type2 digital sound level
meter as standard. The Androidboy1 (www.androidboy1.
blogspot.com) was developed by Smart Tools Co.
The choice of the above three smartphones was based
on the most popular brands available and readily used in
our environment. The iPhone and its Apple applications
though used elsewhere was not applied here because it is
notcommonlyusedinNigeria.
Thetwonoiselevelmeasuringdevices,theSoundLevel
Meter (our standard reference) and the Phone apps (test
devices) were held simultaneously for a period of 10 min
at each location and average noise level recorded for SLM
and mobile phones, respectively.
Noiselevelsintheseareasweretakenforbothday
and night, and areas covered spanned a total of 21 loca-
tions, included residential, business, and market places.
The results were tabulated, and subjected to Pearson cor-
relation and T-test analyses.
The average paired dierences between the standard
(Sound Level Meter) measurements and test (the mobile
phone app readings) were also calculated by subtracting
the values of the tests from the standard readings. These
were also tabulated and used in calculating the variabil-
ity of the test app with reference to the ANSI acceptable
standard error margin for Type 2 devices.[8]
Results
Noiselevelreadingsforbothdaytimeandnightwiththe
SLM and mobile phone showed equivalent values (see
Table 1 and Figures 3 and 4). The daytime readings were
nearly identical in 6 locations and the maximum dier-
ence in values between the two instruments was 3 db,
notedin2locations(Tab l e 1). In both occasions the higher
readings were from the smartphones. In the nighttime
readings, the recordings from the two instruments were
nearly identical in 7 locations while the maximum dif-
ference in value between both instruments was 4dB (only
in a single location) with the higher reading given by the
SLM (Table 1 ). Thus, in 13 out of the 42 readings taken
(31%), the smartphones were similar using the SLM read-
ing as the reference (“true”) measurement.
The Androidboy1 “App” was found to be consistent in
the readings when simultaneously applied to each chosen
environment.
Findings, however, showed4that there was no denite
or predictable pattern to either lower or higher readings
from the mobile phones compared to the SLM vis a vis
the locations; the mobile phones gave lower readings in
some cases and higher values in others in both day-time
and night-time evaluations.
Correlation analysis showed a very strong positive rela-
tionship (r =0.9) in readings between the mobile phone
and SLM in both day-time and night-time assessments.
Analysis of the data by Student’s t-test showed that
there is no signicant dierence between the day-time
and night-time readings (p ࣈ0.12 and 0.58, respectively)
gotten from the SLM and smartphones (see Table 2).
Finally, the consistency of the test instrument (smart-
phone apps) against the standard (SLM) was calculated
from Tab l e 1 , column 6 (dierence in readings (dB)). This
yielded 92.9% using the ANSI guideline for Type 2 sound
measuring devices.[8] Worthy of note is that noise levels
above 90d B are considered high or excessive by interna-
tional standards and some of the readings detected with
this study were marginally above the 90 dBA level.
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D34 T. S. IBEKWE ET AL.
Tab le . Day and night time readings of test (sound level meter phone apps) against the standard (sound level meters) in real time and
uncensored environment.
Daytime(Time) Night-time(Time)
Locations Mobile set (db)
Sound level
Meter (db)
Difference in
readings (db) Mobile set (db)
Sound level
Meter (db)
Difference in
readings (db)
()GARKI −+
()UTAKO +
()WUSE − +
()JABI ++
()GARKI GEN. HOS +
()BERGER + −
()AREA −
()BANNEX +
()ASO DRIVE +
()ASOKORO +
()MAITAMA + −
()WUSE + −
()GWARINPA −
()KUBWA +
()APO − −
()CENTRAL AREA +
()GARKI II −+
()GARKI III +
()GARKI IV +
()GARKI V −
()GARKI VI +
Note:Locations:
) Street
) Hospital
) Market
Figure . Simultaneous day readings of SLM and mobile phone
apps.
Figure . Simultaneous night readings of SLM and mobile phone
apps.
Discussion
Sound level apps’ incorporation into mobile phones
hasbeenspeculatedasaviabletoolforquick,cheap,
convenient,andversatilesoundlevelmonitoringpro-
grams.[14,15] In addition, the benet of citizen participa-
tion arising from widespread mobile use of telephones is
expected to yield tremendous benets in identifying and
tackling noise pollution.[15,16] Unfortunately, there are few
studies regarding the accuracy and consequently, utility of
these smartphone apps.[8]
Our study showed that the mobile phone app android-
boy1 established a strong positive correlation with the
SLM (Table 1 and Figures 2 and 3). In addition, the read-
ings did not show any signicant dierence, for day-time
and night-time evaluations respectively (Tab l e 2 ). The
results were further evaluated with the American National
Standards Institute (ANSI) for Type 2 SLM performance
and accuracy tolerance[7] and the Occupational Safety
and Health Administration (OSHA) quality recommen-
dations.[5] It was deduced that the smartphones’ android-
boy1 app produced readings within ±2db of the SLM
values in 39 of the 42 total recordings (Table 1)equiv-
alent to 92.9% consistency. This agreement was repro-
ducible at dierent hours of the day (Figures 3 and 4).
This level of agreement of the androidboy1 app with the
reference instrument (SLM) suggests the reliability of this
“app” for environmental noise monitoring, i.e., Type A
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JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE D35
Tab le . Paired sample statistics of day and night mobile phone and sound level meter (SLM) simultaneous readings.
Mean N Std. Deviation Std. Error Mean t-test p-value
DAY MOBILE . . . . .
DAY SLM . . .
Night Mobile . . . . .
Night SLM . . .
weighted sounds as a screening test. These ndings, how-
ever,showsomedegreeofcontrastfromastudybyKar-
dous and Shaw.[13] In summary, many android apps were
adjudged not to have the desired functionality for occu-
pational noise assessments. It is important to note that in
the above-referenced study androidboy1 was not among
the android apps selected for the studies. Unlike our
study, their study was a controlled laboratory based. Even
in their study, Kardous and Shaw highlighted the like-
lihood of variation from eld-based measurements (like
our study) due to factors such as temperature and humid-
ity.[13] OurstudyalsocontrastsfromthatbyNastetal.
[10]
study which showed poor performance by 5 apps tested
on the iPhone 4S. However, on utilizing the well-accepted
3-dB and 5-dB time-intensity trading relationships of the
National Institute for Occupational Safety and Health
(NIOSH) recommended standards, respectively,[9] which
were criteria utilized in that study, our ndings showed
that androidboy1 had fairly good accuracy (Ta b l e 2 ).[11]
This is because none of the readings had an error margin,
when compared to the SLM, outside of the 3–5 dB range.
With the rapid expansion and modications of “apps”
softwares, it is reasonable to assume that apps such as
androidboy1 will continue to show improvements in per-
formance that will ensure their ecient applicability as a
screening tool for routine noise level monitoring.
Apartfromavarietyofappsused,otherfactorssuch
as device accuracy derived from the microphone and l-
ter specications are known to a large extent,to determine
sound level measurements.[11] Interestingly, the three dif-
ferent brands of phones (Samsung, Nokia, and Tecno)
tested simultaneously on androidboy1 gave consistent
readings despite the dierence in the brand technologies.
The three smartphones use the microelectromechanical
system microphone, which enhances sound collection; in
their devices. It has sensitivity ranges of 5–17.8 mV/Pa
capableofcapturingsignalsaslowas30dBSPLandas
high as 130dB (signal to noise ratio>60 dB).[13] It also
has a at frequency response similar to the Ceramic Con-
denser present in Type 2 noise meters.[13] This fairly e-
cient microphone device system common to virtually all
smartphones is one of the common factors in favor of
smartphones for this application as against other analog
phone systems.
Furthermore, the importance of appropriate calibra-
tion of these phones cannot be overemphasized and
proper understanding of the dynamic range wherein
accurate measurements can be derived from these smart-
phones.[17–19] An informed choice of an “SLM App sys-
tem” with self /automatic calibration system can be the
gold standard. This is one of the advantages of Android
boy1.Eachtimetheappisupdateditcomeswithauto-
matic re-calibration of the devices. In addition, a re-
calibration process can also be done in between updates
to ensure quality assurance and minimized errors.
The limitations of our study include the fact that only a
single app and three smartphones devices were evaluated.
In addition, the phones had been in use, though for a min-
imal period, prior to the study since we did not procure
brand new phones for the purpose of this study. However,
the above factors were environment driven. Another lim-
itation was the lack of a controlled environment wherein
the performances across various frequencies could have
been assessed in addition to dierent band waves beyond
A-weighted sounds. However, this made our assessment
unique from previous studies because it measured uncen-
sored environmental ambience in real time which is the
major targeted application. Note, that none of our sound
level measurement exceeded 100 dBA during this study.
Conclusions
The use of mobile (smart)phones “apps” for sound level
measurement is a huge potential for environmental noise
monitoring. The androidboy1 “app” p erformance in this
study showed a good correlation and comparative high
sensitivity to the Standard Sound Level Meter (Type 2
SLM device). However there is the need for further stud-
iesbeforewecanconcludethatthesmartphonesandapp
we tested can truly be used as a reliable screening device
for environmental monitoring.
Disclaimer
This research does not intend to endorse any brand of “app”
or “mobile phone” but to demonstrate the potential in similar
products.Theauthorswerenotsupportedorcompensatedin
any way by any phone or app company for this study.
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