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\begin{document}

\title{Acoustic trauma inducing `low frequency' sensorineural hearing loss; A
cross-sectional study among medical students using Pure Tone Audiometry}



\author[1]{Saba Asghar}%
\author[2]{Hurtamina Khan}%
\author[1]{Saima Parveen}%
\author[1]{Tariq Rafi}%
\affil[1]{Jinnah Sindh Medical University}%
\affil[2]{Sindh Medical College and Jinnah Postgraduate Medical Centre}%


\vspace{-1em}



  
  \date{May 07, 2024}


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\selectlanguage{english}
\begin{abstract}
Objectives: This study aimed to ascertain current practices prevalent
among medical students using electroacoustic devices. We also aimed to
determine pattern and frequency of hearing loss among medical students.
Design: Cross-sectional Participants: Students of 3rd year and 4th year
MBBS at Jinnah Sindh Medical University, Karachi, Pakistan were
included. Data collection dated from December 2019 till February 2020
using convenience sampling technique. Setting: Students were invited to
ENT OPD, Jinnah Postgraduate Medical Centre, Karachi. Through a
structured proforma, we recorded practices regarding electroacoustic
devices. We investigated hearing of medical students by tuning fork
tests and Pure Tone Audiometry. Main Outcome Measures: Using SPSS
software version 23 we applied Chi square test, Pearson correlation and
independent t test at 95\% CI and p=\textless{}0.05 as significance
level. Results: A total of 221 students fulfilled inclusion criteria.
96.4\%(n=213) regularly used electroacoustic devices. Students mostly
used insert type earphones connected with a smartphone. More than 30\%
of medical students demonstrated low frequency (0.25-0.5kHz)
sensorineural hearing loss (SNHL). Pearson correlation yielded strong
positive correlation with hearing loss and years of
exposure(p=\textless{}0.001). Male students used electroacoustic devices
more frequently than female students(p=0.01). However, we did not
observe significant difference between their mean thresholds.
Conclusion: Acoustic trauma has been conventionally described to affect
higher frequencies. We found low frequency SNHL among majority of
students. This indicates that specific type of acoustic trauma can
affect particular frequencies on audiogram. KEY WORDS: Low frequency
hearing loss, medical students, Pure Tone Audiometry, personal listening
devices, hearing thresholds, noise induced hearing loss, sensorineural
hearing loss%
\end{abstract}%



\sloppy


\textbf{Abstract:}

\textbf{Objectives:} This study aimed to ascertain current practices
prevalent among medical students using electroacoustic devices. We also
aimed to determine pattern and frequency of hearing loss among medical
students.

\textbf{Design:} Cross-sectional

\textbf{Participants:} Students of 3\textsuperscript{rd} year and
4\textsuperscript{th} year MBBS at Jinnah Sindh Medical University,
Karachi, Pakistan were included. Data collection dated from December
2019 till February 2020 using convenience sampling technique.

\textbf{Setting:} Students were invited to ENT OPD, Jinnah Postgraduate
Medical Centre, Karachi. Through a structured proforma, we recorded
practices regarding electroacoustic devices. We investigated hearing of
medical students by tuning fork tests and Pure Tone Audiometry.

\textbf{Main Outcome Measures:} Using SPSS software version 23 we
applied Chi square test, Pearson correlation and independent
\emph{t}test at 95\% CI and \emph{p} =\textless{}0.05 as significance
level.

\textbf{Results:} A total of 221 students fulfilled inclusion criteria.
96.4\%(n=213) regularly used electroacoustic devices. Students mostly
used insert type earphones connected with a smartphone. More than 30\%
of medical students demonstrated low frequency (0.25-0.5kHz)
sensorineural hearing loss (SNHL). Pearson correlation yielded strong
positive correlation with hearing loss and years of
exposure(p=\textless{}0.001). Male students used electroacoustic devices
more frequently than female students(p=0.01). However, we did not
observe significant difference between their mean thresholds.

\textbf{Conclusion:} Acoustic trauma has been conventionally described
to affect higher frequencies. We found low frequency SNHL among majority
of students. This indicates that specific type of acoustic trauma can
affect particular frequencies on audiogram.

\textbf{KEYWORDS:} Low frequency hearing loss, medical students, Pure
Tone Audiometry, personal listening devices, hearing thresholds, noise
induced hearing loss, sensorineural hearing loss

\textbf{KEY POINTS:}

\begin{enumerate}
\tightlist
\item
  Noise exposure either occupational or recreational is the leading
  preventable cause of hearing impairment
\item
  96.4\% of medical students used electroacoustic devices with insert
  type earphone being the most common connected to a smartphone
\item
  Low frequency (250-500Hz) sensorineural hearing loss was found among
  more than 30\% of medical students
\item
  Most of the students having hearing loss at Pure Tone Audiometry were
  unaware of their hearing loss and did not complain tinnitus
\item
  Specific bandwidth acoustic trauma can affect audiometric frequencies
  other than conventionally described hence require management
  accordingly
\end{enumerate}

\textbf{INTRODUCTION:}

Hearing impairment is the most common sensory disability found among
human beings. \textsuperscript{(1)} After aging, noise exposure either
occupational or recreational is the leading cause. Noise induced hearing
loss (NIHL) once established, is irreversible, only partly manageable
though totally preventable. \textsuperscript{(2)} WHO estimated that 1.1
billion young people (12-35 years) are at risk of hearing loss due to
recreational noise exposure. \textsuperscript{(3)}

Leisure time noise exposure has become a great concern of public health.
Occupational noise hazards have been evidently defined and protective
measures are adopted globally. But no such preventive methods are
clearly devised for the protection of dreadful effects of recreational
noise. \textsuperscript{(4)} Noise induced acoustic trauma has been
conventionally described to effect high tone frequencies when assessed
by Pure Tone Audiometry (PTA). This high tone frequency loss is
graphical representation of response of hair cells in cochlear base.
Based on the guidelines of Health and Safety Executive it was proposed
that the frequency where notch appears in a pure tone audiogram suggests
the specific type of noise to which one was exposed. Intense low
frequency noise can cause maximal loss at lower frequencies while
intense high frequency sound can predominantly affect higher
frequencies. \textsuperscript{(5)}

Hearing difficulty not only hinders the functional capacity of an
individual but also affects the intellectual health of a potential mind.
A large population-based study discovered that low frequency hearing
loss (0.25-0.5kHz) among young and middle age
people\textsuperscript{(6)} while generalized hearing loss among elderly
population considerably affect mental health and quality of
life.\textsuperscript{(7)}

\textbf{Objectives:}

Present study intended to determine the pattern and frequency of hearing
loss among medical students using electroacoustic devices. We also aimed
to ascertain the current practices followed by medical students
regarding use of electroacoustic devices.

\textbf{METHODS:}

\textbf{Operational Definition:} Electroacoustic devices refer to
transducers which convert electrical signals into sound signals e.g.,
handsfree, headphone, Bluetooth handsfree etc.

\textbf{Design:}

Our study had a cross-sectional design. We conducted this study among
medical students at Jinnah Sindh Medical University (JSMU), Karachi.
Data collection dated from December 2019 till February 2020.
Institutional Review Board (IRB) of JSMU approved the study (Ref:
JSMU/IRB/2019/-215).

\textbf{Participants:}

Inclusion criteria were students of 3\textsuperscript{rd} year and
4\textsuperscript{th} year MBBS, either male or female, age between
19-24 years and individuals with normal hearing. Whereas, exclusion
criteria comprised of students not giving consent, those with prior
diagnosis of hearing loss, type I diabetes mellitus, acute upper
respiratory tract infections, acute or chronic ear infections, allergic
rhinitis, positive history for ototoxic drugs, past medical history of
meningitis, enteric fever in childhood, past surgical history for cleft
lip or palate, using hearing aid and family history of hearing loss.

\textbf{Sample size:}

We employed non-probability convenience sampling technique. For sample
size calculation we used open Epi calculator. A related study reported
84\% prevalence of hearing loss among mobile phone
users.\textsuperscript{(10)} Using this information at 95\% CI and error
of \selectlanguage{ngerman}±5\%, we figured out sample size of 194.

\textbf{Setting and Hearing Assessment:}

We invited students to the Ear, Nose and Throat (ENT) OPD, Jinnah
Postgraduate Medical Centre, Karachi (JPMC) for tuning fork tests (TFTs)
and PTA. We explained whole procedure to the students and acquired
informed consent on individual basis. Using a structured proforma, we
collected sociodemographic information, electroacoustic device usage
history and relevant medical and surgical history from each participant.
Sociodemographic data included age, gender, year of study and residence.
We also asked about type of electroacoustic device (insert type
earphones, supraural headphones or Bluetooth handsfree), per day
duration, source to which these devices were connected and using since
when.

Postgraduate trainees of ENT performed Rinne test and Weber test on each
participant with a 512 Hz tuning fork. We regarded centralized hearing
of the tuning fork as normal while base of tuning fork placed at
forehead or upper incisors. For Rinne test we applied loudness
comparison technique. In which we kept the base of tuning fork on
mastoid process to assess bone conduction (BC). For air conduction (AC)
we located prongs of tuning fork lateral to the external auditory canal
(EAC). We considered positive (normal) result when air conduction proved
better than bone conduction (AC \textgreater{}BC).

Immediate next to TFTs we sent our students for PTA. We instructed them
regarding the test procedure. Trained audiometrists performed PTA in a
soundproof booth. They assessed each participant first for air
conduction (AC) at octave frequencies i.e. 250 Hz, 500 Hz, 1000 Hz, 2000
Hz, 4000 Hz and 8000 Hz. To differentiate the type of hearing loss from
conductive to sensorineural, they also investigated bone conduction when
AC thresholds were beyond normal range. Significant air-bone gap was
considered greater than 15 dB (decibel) between air and bone conduction
thresholds. Test frequencies for bone conduction were from 500 Hz to
4000 Hz. They generated the findings of PTA on an audiogram. To classify
hearing loss at each frequency we applied WHO grading of hearing
impairment. Where normal was 25 dB or less, mild hearing loss from 26-40
dB, moderate from 41-60 dB, severe from 61-80 dB while profound hearing
loss including deafness was 81dB or greater.

\textbf{Main Outcome Measures:}

We did data entry and analysis using IBM SPSS Statistics, version 23
(IBM Corp.). We carried out descriptive statistical analysis to obtain
the frequencies, mean and standard deviation (S.D). We applied Chi
square test and Fischer exact test to find the association of
electroacoustic device use with independent variables like gender and
year of study. We utilized Pearson correlation to find the association
between hearing loss and electroacoustic device usage. We also employed
independent \emph{t} test to compare the means at octave frequencies
among male and female students. We kept \emph{p} value \textless{}0.05
and 95\% CI as level of statistical significance. We described our
findings using STROBE reporting guidelines.

\textbf{RESULTS:}

A total of 246 students participated in the study. However, only 221
satisfied the inclusion criteria. We excluded rest as exclusion
criteria. Mean age of students was 21 years (S.D: ±0.927; Range: 20-24).
Out of 221, 74.7\% (n=165) were females while 25.3\% (n=56) were males.
Students from 3\textsuperscript{rd} year and 4\textsuperscript{th} year
were almost equal (49.3\% Vs. 50.7\% respectively). Among recruited
sample, 96.4\% (n=213) were regularly using electroacoustic devices.
With insert type earphones being the most common (73.8\%; n=163).
Followed by Bluetooth handsfree (14\%; n=31) and supra-aural headphones
(5\%; n=11). Students reported smartphone (90\%; n=199) as the most
frequently used source for listening to these devices, followed by
laptop (32.6\%; n=72) and tablet (5.9\%; n=13).

Listening duration of 44.8\% (n=99) medical students stood between one
to two hours per 24 hours. Nevertheless, 19.5\% (n=43) exceeded three
hours per day. In our study, 26.2\% (n=58) undergraduates practiced high
volume setting for listening. Near half of the users (47.9\%; n=106)
were experiencing electroacoustic devices beyond five years. Wherein
22.6\% (n=24) were enjoying their use for 10 or more years.

We found statistically significant difference among average listening
duration between male (165.77 ± 103.39 minutes) and female students
(120.09 ± 121.76 minutes) \emph{t} (219) = 2.516, \emph{p} =0.013. We
did not observe any significant difference for volume setting (p=0.851)
and duration since years (p=0.145) with gender. Likewise, no
statistically significant difference existed between volume setting
preference (p=0.977) and duration since years (p=0.820) with year of
study. TABLE I represents the listening habits of our study sample.

Among electroacoustic device users Rinne test was negative (BC
\textgreater{}AC) in 3 ears on right side. Weber test was lateralized in
7\% (n=15) to right ear and same for the left ear. Almost one third of
medical students who were using electroacoustic devices suffered mild
sensorineural hearing loss (SNHL) at frequencies 250 Hz (31.9\%; n=68)
and 500 Hz (31.5\%; n=67) in right ear. In left ear, 29.1\% (n=62) at
frequency of 250 Hz while 23\% (n=49) at 500 Hz fall under mild SNHL. In
our study only 5.6\% (n=12) and 6.6\% (n=14) students suffered mild
(sensorineural) hearing loss at 4kHz and 8kHz in right ear,
respectively. There was no air bone gap in any of the cases. TABLE II
summarizes the hearing thresholds of electroacoustic device users at
audiometric octave frequencies.

We applied Pearson correlation to find association of hearing loss with
per day listening duration and listening years. We did not find any
significant correlation with per day duration. However, we noticed
statistically significant association between listening years and
hearing loss. Positive correlation existed at 500Hz (p=\textless{}.001),
1000Hz (p=\textless{}.001), 2000Hz (p=\textless{}.001) in right ear. In
left ear, there was significant positive correlation at 250Hz
(p=\textless{}.001), 500Hz (p=\textless{}.001), 1000Hz (p=0.04) and
2000Hz (p=\textless{}.001).

Independent t test carried at 95\% CI did not show any significant
difference between mean hearing thresholds of male and female students.
TABLE III displays the means at octave frequencies among male and female
students.

\textbf{DISCUSSION:}

To the best of our information (based on published literature), present
study is the largest to be conducted in Pakistan among medical students
using PTA for hearing assessment. Our study comprised 221 participants
with age group between 20-24 years (Mean±S.D: 21±0.927). Similar range
was mentioned in comparable studies. \textsuperscript{(11,12)} Male to
female ratio was 1:3. This represents comparative larger number of
female students studying in medical colleges of this region.

We found a high prevalence (96.4\%) of electroacoustic device usage
amongst medical students. Rekha et al. reported personal listening
device (PLD) use by medical students with frequency of 86.1\% on daily
basis \textsuperscript{(13)}. A study from Hamadan University of Medical
Sciences, Iran stated 91.2\% prevalence of PLD
use.\textsuperscript{(14)} A recent study conducted by Basu et al.
narrated 5.4\% medical students never used an electroacoustic
device.\textsuperscript{(15)} In our study only 3.6\% students denied
their use of personal listening devices. This high prevalence of
electroacoustic device use can be attributed to current educational
practices followed by medical students. Such as online lectures and 3D
animated content available for vast academic topics.

Participants of our study preferred insert type earphones. The most
widely used source was smartphone. Parallel studies observed the similar
preferences. \textsuperscript{(13,14)} A study from Jeddah stated that
almost all the medical students used a smartphone.\textsuperscript{(16)}
Easy availability of smartphones, comfortable portability along with
broad range compatibility for wide variety of earphones are the possible
attractions making them the first choice among their users.

Our study showed that hearing impairment was strongly correlated with
the prolonged exposure to listening devices. Near half of our
participants were using electroacoustic devices for more than five
years. However, previous studies reported variable results for
association between hearing loss and listening
duration.\textsuperscript{(11,12)} Volume preferences did not vary
considerably from alike studies. \textsuperscript{(13,14)}

We found less prevalence of self-reported hearing symptoms (tinnitus
9.5\%, vertigo 2.7\%) in comparison with other
studies.\textsuperscript{(8,13,14)} Interestingly, we also noted that
majority of medical students who displayed hearing loss in PTA were not
experiencing tinnitus and even not aware of their hearing impairment.
For example, in right ear at 500Hz, 88.4\% (n=61) having mild hearing
loss did not complain tinnitus.

Upon PTA, around one third of our medical students showed mild sensory
hearing loss at lower frequencies (250 Hz and 500 Hz). Similar pattern
of low frequency hearing loss was detected in a study conducted among 56
medical students \textsuperscript{(9)}. A study was performed among 136
employees of a Malaysian telecommunication company. This revealed
impaired hearing in 21.2\% of the personnel. An equal distribution of
hearing loss in low, middle, and high frequencies was
noticed.\textsuperscript{(17)} The possible explanation to this
distinctive pattern of low frequency loss might be due to the intensity
of noise to which they were exposed as indicated by McBride et
al.\textsuperscript{(5)} The participants of our study were medical
students who might be using electroacoustic devices for educational
purposes mostly. The staff of telecommunication company used headphones
for receiving phone calls which involve conversational frequencies. The
intensity, pitch and bandwidth of sound generated in such content differ
considerably from that produced in music and occupational noise. In
addition, a prolonged exposure up to 8 hours per day over 85dB
(Permissible Exposure Limit) is required to produce characteristic
pattern of NIHL. \textsuperscript{(18)} None of our study participants
reached this limit hence traditional notch at frequency of 4kHz was not
found among most of the users.

In our study we found mild hearing loss (26-40dB) in majority of cases.
Cochlear apex is responsible for perceiving low frequency sounds. Halpin
et al. demonstrated that audiogram inherits some limitations when
assessing low frequency SNHL especially when high frequency thresholds
are within normal range. This is due to asymmetric spread of stimulus
along basilar membrane of cochlea. Healthy hair cells in the middle or
base of cochlea get stimulated and generate the response for lower
frequencies. The upper limit being 50dB in such
cases.\textsuperscript{(19)}

This study has certain unavoidable limitations owing to its
cross-sectional study design and non-probability sampling technique.
This was a single centre study hence we cannot generalize the findings.
This study therefore suggests correlation but cannot confirm causation.

\textbf{CONCLUSION:}

We investigated the hearing thresholds of medical students using PTA.
Majority of students demonstrated low frequency SNHL. These findings are
contrary to the conventionally described high frequency hearing loss in
noise trauma. This indicates that acoustic trauma not only affects high
frequencies but can also impact other hearing thresholds as well and
needs hearing rehabilitation accordingly. Moreover, protective measures
should be taken to avoid this type of hearing loss which is completely
preventable.

\textbf{CONFLICT OF INTREST:}

Authors declare no conflict of interest

\textbf{FUNDING STATEMENT:}

Authors have no funding disclosures to declare

\textbf{DATA AVAILIBILTY STATEMENT:}

The data that support the findings of our study are available on request
from the corresponding author. The data are not publicly available due
to privacy or ethical restrictions.

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\textbf{TABLES:}

\textbf{TABLE I. Listening Habits of the Study Sample}\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
Total study population (N) & 221\tabularnewline
\midrule
\endhead
Characteristics & No. (\%)\tabularnewline
Mean age (S.D) & 21 (\selectlanguage{ngerman}±0.927)\tabularnewline
Gender &\tabularnewline
Male & 56 (25.3)\tabularnewline
Female & 165 (74.7)\tabularnewline
Year of study &\tabularnewline
3\textsuperscript{rd} year & 109 (49.3)\tabularnewline
4\textsuperscript{th} year & 112 (50.7)\tabularnewline
Electroacoustic device use since &\tabularnewline
Never & 8 (3.6)\tabularnewline
1-2 years & 35 (15.8)\tabularnewline
3-4 years & 72 (32.6)\tabularnewline
5-6 years & 52 (23.5)\tabularnewline
\textgreater{}7 years & 54 (24.4)\tabularnewline
Volume level &\tabularnewline
No use & 8 (3.6)\tabularnewline
Low & 10 (4.2)\tabularnewline
Medium & 145 (65.6)\tabularnewline
High & 58 (26.2)\tabularnewline
Listening time per day &\tabularnewline
No use & 8 (3.6)\tabularnewline
Less than 1 hour & 39 (17.6)\tabularnewline
1-2 hours & 99 (44.8)\tabularnewline
2-3 hours & 32 (14.5)\tabularnewline
\textgreater{}3 hours & 43 (19.5)\tabularnewline
Other symptoms (if any) &\tabularnewline
Tinnitus & 21 (9.5)\tabularnewline
Vertigo & 6 (2.7)\tabularnewline
Earache & 11 (5)\tabularnewline
Headache & 39 (17.6)\tabularnewline
\bottomrule
\end{longtable}



\textbf{TABLE II: Hearing Thresholds of Pure Tone Audiometry at Octave
Frequencies among Electroacoustic Device Users (n=213)}\selectlanguage{english}
\begin{longtable}[]{@{}lllll@{}}
\toprule
\begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\textbf{Test Frequency}\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\textbf{Normal} \textbf{(\textless{}25dB)}\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\textbf{Mild HL11HL= Hearing Loss} \textbf{(26-40dB)}\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\textbf{Moderate HL} \textbf{(41-60dB)}\strut
\end{minipage} & \begin{minipage}[b]{0.19\columnwidth}\raggedright\strut
\textbf{Severe HL} \textbf{(61-80dB)}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Right ear 250 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
139 (65.3)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
68 (31.9)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
6 (2.8)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Right ear 500 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
145 (68.1)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
67 (31.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Right ear 1000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
198 (93)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
15 (7)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Right ear 2000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
202 (94.8)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
10 (4.7)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Right ear 4000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
200 (93.9)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
12 (5.6)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Right ear 8000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
196 (92)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
14 (6.6)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
2 (0.9)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Left ear 250 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
150 (70.4)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
62 (29.1)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Left ear 500 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
163 (76.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
49 (23)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Left ear 1000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
199 (93.4)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
13 (6.1)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
-\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Left ear 2000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
199 (93.4)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
12 (5.6)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Left ear 4000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
198 (93)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
13 (6.1)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
Left ear 8000 Hz\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
194 (91.1)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
16 (7.5)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
2 (0.9)\strut
\end{minipage} & \begin{minipage}[t]{0.17\columnwidth}\raggedright\strut
1 (0.5)\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}



\textbf{TABLE III: Mean thresholds at octave frequencies among male and
female students}\selectlanguage{english}
\begin{longtable}[]{@{}lllllll@{}}
\toprule
\textbf{Test frequency} & \textbf{250 Hz} & \textbf{500 Hz} &
\textbf{1000 Hz} & \textbf{2000 Hz} & \textbf{4000 Hz} & \textbf{8000
Hz}\tabularnewline
\textbf{Right ear} & \textbf{Right ear} & \textbf{Right ear} &
\textbf{Right ear} & \textbf{Right ear} & \textbf{Right ear} &
\textbf{Right ear}\tabularnewline
Male & 26.66 & 23.98 & 22.02 & 21.0 & 22.21 & 22.86\tabularnewline
Female & 27.10 & 24.88 & 22.82 & 20.58 & 21.41 & 22.09\tabularnewline
P value & 0.63 & 0.31 & 0.20 & 0.56 & 0.35 & 0.46\tabularnewline
\textbf{Left ear} & \textbf{Left ear} & \textbf{Left ear} & \textbf{Left
ear} & \textbf{Left ear} & \textbf{Left ear} & \textbf{Left
ear}\tabularnewline
Male & 24.89 & 24.34 & 22.02 & 21.86 & 22.86 & 22.34\tabularnewline
Female & 26.2 & 24.38 & 21.78 & 20.62 & 20.88 & 22.22\tabularnewline
P value & 0.11 & 0.96 & 0.79 & 0.31 & 0.09 & 0.90\tabularnewline
\bottomrule
\end{longtable}

\selectlanguage{english}
\FloatBarrier
\end{document}

