Context.— Hearing loss in children influences the development of communication
and behavioral skills, but few studies in the United States have used pure-tone
audiometry to derive hearing loss prevalence estimates for children.
Objective.— To describe the prevalence of hearing loss among US children by sociodemographic
characteristics, reported hearing loss, and audiometric screening factors.
Design.— National population-based cross-sectional survey with an in-person interview
and audiometric testing at 0.5 to 8 kHz.
Setting/Participants.— A total of 6166 children aged 6 to 19 years completed audiometry in
the mobile examination center of the Third National Health and Nutrition Examination
Survey conducted between 1988 and 1994.
Main Outcome Measure.— Hearing loss, defined as audiometric threshold values of at least 16-dB
hearing level based on a low or high pure-tone average.
Results.— A total of 14.9% of children had low-frequency or high-frequency hearing
loss of at least 16-dB hearing level, 7.1% had low-frequency hearing loss
of at least 16-dB hearing level, and 12.7% had high-frequency hearing loss
of at least 16-dB hearing level. Most hearing loss was unilateral and slight
in severity (16- to 25-dB hearing level). Of those with measured hearing loss,
10.8% were reported to have current hearing loss during the interview.
Conclusions.— This analysis indicates that 14.9% of US children have low-frequency
or high-frequency hearing loss of at least 16-dB hearing level in 1 or both
ears. Among children in elementary, middle, and high school, audiometric screening
should include low-frequency and high-frequency testing to detect hearing
loss.
A CHILD'S ABILITY to hear influences the development of communication
and behavioral skills that affect educational experience and relationships
with other people.1,2 Public health
screening and intervention play an important role in improving the health
(including hearing status) and well-being of children. Children are most often
administered audiometric evaluations at speech frequencies as part of routine
physical examinations or in school settings. The majority of conductive hearing
loss affects the low frequencies, while the majority of sensorineural hearing
loss affects the high frequencies.3 Impacted
cerumen, a foreign body, edema of the auditory canal, and otitis media are
just a few of many possible causes of conductive hearing loss among children.2,3 Noise, medications, meningitis, and
congenital syphilis are among the many possible causes of sensorineural hearing
loss among children.2,3 Studies
have shown that high-frequency hearing loss from noise exposure during childhood
can lead to further hearing loss from acute or chronic noise exposure at older
ages.4
The effect of noise in the environment on hearing levels has gained
increased recognition.5 In the United States,
few studies have included a range of high-frequency audiometry (≥3 kHz)
from which hearing loss prevalence estimates can be derived for children.6-9 Recent
data from the Third National Health and Nutrition Examination Survey (NHANES
III), conducted from 1988 to 1994 by the National Center for Health Statistics
of the Centers for Disease Control and Prevention, offer the opportunity to
examine both low and high audiometric frequencies and to evaluate the presence
of hearing loss by sociodemographic characteristics in a national sample of
children aged 6 to 19 years.
NHANES III used a stratified multistage probability design.10 The sample consisted of approximately 40000 people
who were representative of the US civilian noninstitutionalized population
2 months of age or older.10 National population
estimates, as well as estimates for the 3 largest racial and ethnic subgroups
in the US population (non-Hispanic white, non-Hispanic black, and Mexican
American), can be derived from the 6-year survey.10
Data were collected through household interviews, and standardized audiometric
examinations were conducted in a mobile examination center.11
The NHANES III protocol for audiometry included persons aged 6 to19 years,
and did not include otoscopic examinations.
Audiometry was conducted in a sound-treated room in the mobile examination
center by trained examiners using a standardized protocol. An audiometer (model
GSI 16; Grason-Stadler, Milford, NH) was calibrated with the same specifications
at the start and end of testing at each field location.12
Additional calibration audiometric equipment included a sound level meter
(model 2235; B&K, Denmark), an artificial ear coupler (model 4151, B&K),
a 2.5-cm condenser microphone (model 4144, B&K), a 1.3-cm condenser microphone
(model 4155, B&K), an octave band filter (model 1624, B&K), an acoustic
calibrator (model 1624, B&K), an adapter (model DB 0375, B&K), and
a 500-g weight.12
Air-conduction thresholds were measured for each ear at 0.5, 1, 2, 3,
4, 6, and 8 kHz, with testing repeated at 1 kHz.12
The correlation of the threshold for the 1-kHz first test with the retest
was 0.9 (P<.001) for the left and right ears of
each child. The 1-kHz first test was the value used for this analysis.
If a subject had air-conduction threshold values at a given frequency
that differed by 40 dB or more between ears, masking was performed to assure
accuracy in measurement.13 Threshold values
were obtained between −10- and 110-dB hearing level (dB HL). If no response
was obtained at the limits of the test protocol, a threshold of 105-dB HL
was recorded for statistical purposes.13 In
this sample, 106 children (1.7%) had masking performed. If present, the masked
values were used for this analysis.
Sociodemographic Variables and Hearing-Related Covariates
Age at interview was categorized as 6 to 11 years or 12 to 19 years.
Race-ethnicity was grouped as non-Hispanic black, non-Hispanic white, or Mexican
American. The "all other" race-ethnicity category (eg, other Hispanics, Asians,
and Native Americans) was too small to be analyzed separately, but was included
in all totals.14 These 4 race-ethnicity groups
are mutually exclusive. The poverty-income ratio (PIR) was defined as the
total family income divided by the poverty threshold, as determined by the
US Bureau of the Census, for the year of the interview.14
To be consistent with major government food assistance programs that use a
PIR cutoff of 1.3 to determine eligibility, PIR categories used in analyses
were low (PIR ≤ 1.3), middle (1.3 < PIR ≤ 3.5), and high (PIR > 3.5).14 No family income data were available for 8.6% of
the children tested.
Self-reported hearing status was determined from questions administered
during the household interview to parents or guardians of children aged 6
to 16 years. Youths aged 17 to 19 years were also asked about hearing status
as part of the adult questionnaire during the household interview. Prior to
the audiometric examination, a screening questionnaire was administered to
determine test exclusions and to assess factors that may affect test results
(draining ears, cold, sinus or earache problems, exposure to music through
use of earphones or headphones, and exposure to very loud noise within the
past 24 hours). Parents or guardians responded to these questions for children
aged 6 to 12 years. Youths aged 13 to 19 years responded for themselves. Responses
to the household interview and screening questions were dichotomized into
yes and no categories.
Of the 6908 children aged 6 to 19 years who were interviewed in NHANES
III, 6497 children (94.1%) were also examined. Children who were interviewed
but not examined did not differ by age, sex, race-ethnicity, or PIR from children
who were interviewed and examined. Of the 6497 children examined in NHANES
III, 331 (5.1%) were excluded from our analyses because they missed all audiometric
items (n=256), had only 1 ear tested (n=36), or had other incomplete audiometric
testing (n=39). Of the 331 children excluded from this analysis, 44 were excluded
from audiometry on the ear(s) with drainage per the NHANES III protocol.11,12 Children with incomplete data did
not differ by age, sex, race-ethnicity, or PIR from children with complete
data. A total of 6166 children were available for analysis.
The traditional pure-tone average (PTA) for speech-affected frequencies
was calculated by averaging thresholds per ear obtained at 0.5, 1, and 2 kHz,
and was labeled as the low pure-tone average (LPTA) for this report.2,15 A high pure-tone average (HPTA) was
calculated by averaging thresholds per ear obtained at frequencies of 3, 4,
and 6 kHz.15,16 For this report,
low-frequency hearing loss (LFHL) was defined as LPTA of at least 16-dB HL,
and high-frequency hearing loss (HFHL) was defined as HPTA of at least 16-dB
HL. Low pure-tone averages and HPTAs were also grouped into finer categories
of hearing capacity2,17: normal
(−10- to 15-dB HL), slight loss (16- to 25-dB HL), mild loss (26- to
40-dB HL), moderate loss (41- to 65-dB HL), severe loss (66- to 95-dB HL),
and profound loss (≥ 96-dB HL). Because of the very small numbers in these
finer categories, the categories were collapsed. Categories of hearing were
examined by left and right ear, and by better ear (ear with lower PTA) and
worse ear (ear with higher PTA). The better ear definition includes children
with unilateral hearing loss as normal, whereas the worse ear definition does
not. Hearing thresholds were evaluated at each tested frequency. The worse
ear HPTAs and LPTAs were examined by reported sociodemographic characteristics.
Reported hearing loss and responses to the audiometric screening questions
were analyzed by the categories of low-frequency and high-frequency hearing
loss. Odds ratios for the risk of hearing loss were calculated for the screening
questions.
All prevalence estimates and 95% confidence intervals were derived using
SUDAAN, a statistical package compatible with SAS that accounts for the complex
survey design and weights.18,19
In estimating the number of children in the US population with hearing loss,
we adjusted estimates to the 1991 US census data for the population of children
aged 6 to 19 years.14
The prevalence of either LFHL or HFHL of at least 16-dB HL in 1 or both
ears among US children was 14.9% (>7 million children). The prevalence of
both LFHL and HFHL was 4.9%. The prevalence of LFHL was 7.1% (1.5% bilateral
and 5.6% unilateral) (Table 1).
Of all children, the proportion with slight LFHL in either ear was 5.7% (Table 1), mild to moderate was 1.4%, and
severe to profound was 0.3%. The prevalence of HFHL was 12.7% (3.1% bilateral
and 9.6% unilateral) (Table 2).
Of all children, the proportion with slight HFHL in either ear was 10.5% (Table 2), mild to moderate was 2.6%, and
severe to profound was 0.4%.
Based on the better ear, 1.3% to 2.8% of all children had hearing loss
of at least 16-dB HL at the individual frequencies of 0.5, 1, 2, 3, and 4
kHz. The prevalence of hearing loss in the better ear was highest at 6 kHz
(5.8%) and 8 kHz (7.6%). Based on the worse ear, 5.5% to 10.6% of all children
had hearing loss at 0.5, 1, 2, 3, and 4 kHz (Table 3). The prevalence of hearing loss in the worse ear was highest
at 6 kHz (24.7%) and 8 kHz (27.3%) (Table
3).
The hearing loss prevalence estimates based on the worse ear for LFHL
and HFHL by various sociodemographic characteristics are presented in Table 4. Overall, there was little variability
in the prevalence of LFHL by sex, age group, race-ethnicity, or PIR. There
were, however, some pronounced differences in the prevalence of HFHL by sociodemographic
characteristics. The prevalence of HFHL was higher among males than females
(Table 4). The prevalence of HFHL
in the age group of 6 to 11 years did not differ by sex. However, in the age
group of 12 to 19 years, the prevalence of HFHL was 15.9% for males as compared
with 10.3% for females. The prevalence of HFHL differed only slightly by race-ethnicity
(Table 4). Mexican American children
had the highest prevalence of HFHL (15.1%) as compared with non-Hispanic black
children (11.7%) and non-Hispanic white children (12.3%). Children from low-income
families had greater HFHL (16.3%) than either children from middle-income
families (12.7%) or high-income families (7.9%), as presented in Table 4.
Of those children who had measured LFHL or HFHL of at least 16-dB HL,
only 10.8% were reported to have current hearing loss at the time of household
interview. Of the 3.4% of children who were reported to have current hearing
loss, almost half had measured LFHL or HFHL. However, of children who were
reported to have normal hearing, 13.8% had measured hearing loss at the time
of audiometric testing (6.0% had LFHL and 11.6% had HFHL).
The prevalence of responses to audiometric screening questions are reported
in Table 5. These results are
limited to children who had reported answers to the screening questions. Use
of headphones or earphones to listen to loud music in the past 24 hours was
reported by 10.2%, and exposure to a loud noise in the past 24 hours was reported
by 6.0%. These 2 factors did not appear to affect the prevalence of measured
LFHL or HFHL. The presence of a cold or sinus problem the day of audiometric
testing was reported by 14.8%, and the presence of buzzing or ringing in the
ear(s) on the day of audiometric testing was reported by 3.2%. Children with
these 2 factors had a higher prevalence of measured LFHL but not of measured
HFHL. The presence of an earache in the past week was reported by 3.7%, and
the presence of tube(s) in the ear(s) was reported by 1.6%. Children with
these 2 factors had a higher prevalence of LFHL and HFHL than children without
these conditions or symptoms. For example, children reported to have had an
earache in the past week were 3 times more likely to have LFHL than children
who were not reported to have had an earache in the past week.
This study estimated hearing ability in a range of 0.5 to 8 kHz in a
sample that is representative of the US population of children aged 6 to 19
years. The data from NHANES III demonstrate that approximately 14.9% (more
than 7 million) of US children have LFHL or HFHL of at least 16-dB HL. The
majority of hearing loss was determined to be unilateral and slight with respect
to severity. Unilateral hearing loss in children impacts speech perception,
learning, self-image, and social skills.1 Slight
hearing loss affects children in classrooms and other reverberant listening
environments in which a child with transient auditory dysfunction can have
difficulty perceiving and understanding speech sounds.1,2
Children with unilateral hearing loss or with slight hearing loss may require
interventions such as speech therapy and consideration of the need for a hearing
aid.1,2 Because the decibel scale
is exponential, even a slight decibel change in a child's hearing threshold
at any frequency can significantly affect that child's ability to hear.4
The measurement of hearing thresholds at low and high frequencies for
both ears provides an extensive assessment of a child's ability to hear clear,
distorted, quiet, and noisy sounds that are a part of the everyday environment.20,21 Children with conductive hearing
loss may have difficulty hearing low frequencies such as human speech, while
children with sensorineural hearing loss may have difficulty hearing high
frequencies such as doorbells, telephones, or a high-pitched voice.2,3 In this analysis, the proportion of
children exhibiting HFHL was higher than that of children exhibiting LFHL.
Although this analysis did not determine the etiology of hearing loss, the
affected frequencies are described.
As in previous studies, this study shows unilateral hearing loss (hearing
loss in only 1 ear) to be more prevalent among children than bilateral hearing
loss (hearing loss in both ears).16,22
Prevalence estimates of hearing loss that are based on measurements in the
better ear define children with unilateral hearing loss as having normal hearing.
Therefore, estimates of hearing loss that are based on measurements in the
worse ear, as used in Table 4
of this report, may be a more accurate indicator of the number of US children
who need intervention at home and school to prevent hearing loss from impairing
their development.16,23
Of those children who had measured LFHL or HFHL, only 10.8% reported
having current hearing loss at the time of the household interview. This difference
may be explained by several factors. First, a child with transient or temporary
hearing loss at the time of audiometric testing may not have had the hearing
loss at the time of the household interview, which could have been as many
as 8 weeks prior to the examination. In addition, a child may have had temporary
or transient hearing loss at the time of the interview, but not at the time
of the examination. Second, hearing loss was reported by a parent or guardian
for youths aged 6 to 16 years and thus, may not have reflected the true hearing
status as recognized by the child. Third, because the majority of detected
hearing loss was in the slight range, parents, as well as children aged 17
to 19 years who answered questions on hearing loss for themselves, may not
have recognized hearing loss.1,24
Although some children do not recognize hearing loss, these children may be
missing listening information and are at risk for learning disabilities.1,2 The overall prevalence of hearing difficulty
by self-report (3.4%) from the NHANES III household interview is almost double
that found in the 1990-1991 National Health Interview Survey Hearing Supplements
for children aged 3 to 17 years (1.8%).25
Other studies have reported results of high-frequency testing9,24; however, to our knowledge, no nationally
representative study has examined hearing at high frequencies in children
since the National Health Examination Surveys (NHES) conducted from 1963 to
1970.7,8 The documentation of
the results of NHES audiometric testing are presented in a different format
with different definitions and methods than the present study. Thus, the results
of this analysis cannot be compared with documented analyses of NHES audiometric
data. Caution should be used when comparing results of hearing loss studies
because of the variations used in determining screening methods and definitions
of hearing loss (eg, different age ranges, frequencies tested, decibel levels
used to screen, and some studies only include the better ear).
The following findings are in agreement with our results that more children
have hearing loss in high frequencies than in low frequencies. Holmes et al9 found that 7% of 342 Florida students sampled (aged
10-20 years) had hearing loss of at least 25-dB HL at the individual frequencies
of 1, 2, and 4 kHz in 1 or both ears, and 17% had hearing loss when 6 kHz
was included. These findings are similar to our findings that 7.1% of US children
aged 6 to 19 years had either unilateral or bilateral LFHL, and 12.7% had
HFHL. Cozad et al24 found that 10.6% of their
sample of children aged 6 to 18 years in Kansas had hearing loss greater than
10-dB HL at the individual frequencies of 0.25, 0.5, 1, 2, 3, 4, 6, and 8
kHz in 1 or both ears, with 34.4% of the 10.6% failing low-frequency screening
and 64.6% of the 10.6% failing high-frequency screening.
Including 3, 4, and 6 kHz for audiometric screening and PTA calculations
results in a more accurate measurement of hearing loss throughout childhood
and adolescence, especially among those children who do not recognize that
they have hearing loss.4,15,16,24,26,27
Hearing loss may be detected early by looking at each tested frequency, particularly
for noise-induced hearing loss, which initially involves 1 or more frequencies
in the 3- to 6-kHz range.4 The audiometric
screening questions regarding noise did not show an association with temporary
threshold shifts. However, historically, noise-induced hearing loss is the
most common cause of permanent HFHL.3 Exposure
to very loud noises may explain the prevalence of HFHL (low frequencies are
initially unaffected by noise).3,4,15,16,20
Persons with hearing loss in the high frequencies need to be advised as to
appropriate hearing protection and methods to minimize noise exposure (eg,
earplugs at a noisy concert or in shop class).28
Otitis media is common in childhood,1,2
and may explain why 3.7% of all children were reported to have had an earache
in the past week. Due to the absence of an otoscopic examination, temporary
or transient hearing loss due to an obstructed auditory canal (eg, impacted
cerumen) could not be determined. Conductive hearing losses due to pathology
in the outer and middle ear are usually temporary and can fluctuate greatly.28,29 Nonetheless they can have detrimental
effects educationally and on the development of speech and language.1,31 These hearing losses need to be treated
medically to afford the child the advantages of better hearing.29,30
More studies are needed to look at sociodemographic characteristics
and hearing loss. The findings of this study are consistent with other findings
that male adolescents have a greater prevalence of HFHL than do females.1,24 Although this study found no difference
by race-ethnicity for LFHL, Mexican American children had more HFHL than non-Hispanic
white or non-Hispanic black children. Lee et al31
found that Mexican American children (2.8%) have more bilateral LFHL than
African American children (1.7%) or non-Hispanic white children (1.6%). Our
results also show children with low PIRs to have more HFHL than children with
middle or high PIRs. However, PIR is a variable that other hearing loss studies
need to explore.
The screening questions administered the day of the audiometric examination
were designed to assess factors that may affect hearing status. The use of
headphones or earphones in the past 24 hours and exposure to loud noise in
the past 24 hours did not appear to affect the prevalence of measured LFHL
or HFHL. Children who were reported to have a cold or sinus problem on the
day of the examination had a marginally higher prevalence of LFHL. Children
who were reported to have buzzing or ringing in the ear(s) on the day of the
examination had a higher prevalence of LFHL. However, children who reported
having had an earache in the past week or tube(s) in the ear(s)on the day
of the examination had a higher prevalence of LFHL and HFHL. A child with
a tube in an ear is most likely being treated for chronic ear infections.2 Because of the limitations of the survey, we cannot
discern what proportion of children have temporary hearing loss.
The results of this study suggest a need for further research to explain
differences in the prevalence of hearing loss in high frequencies among children
by age group, sex, race-ethnicity, and PIR. These differences may be related
to variations in environmental exposures (eg, noisy hobbies, smoking).22,23,32 Further studies also
are needed to assess differences in hearing thresholds over time. Currently,
hearing screening in schools is commonly performed in elementary grades at
1, 2, and 4 kHz.1 If hearing loss is identified
early, particularly when it may be due to factors such as noise exposure,
education and counseling may help prevent educational difficulties and further
potentially handicapping hearing loss from developing, and may help maintain
residual hearing.1,2,28
With 14.9% of US children aged 6 to 19 years having LFHL or HFHL in 1 or both
ears, audiometric screening should include low-frequency testing (0.5, 1,
and 2 kHz) and high-frequency testing (3, 4, and 6 kHz) to detect hearing
loss among children in elementary, middle, and high school.
1.Anderson KL. Keys to effective hearing conservation programs: hearing status of
school age children. In: Cherow E, ed. Proceedings of the ASHA Audiology Superconference.
ASHA. 1992;21:38-47.
2. Disorders of the eye and ear. In: Behrman RE, Kliegman RM, Nelson WE, Vaughan VC, eds. Nelson
Textbook of Pediatrics. Philadelphia, Pa: WB Saunders Co; 1992:1602-1608.
3.Gulya AJ. Evaluation of impaired hearing. In: Goroll AH, May LA, Mulley AG Jr, eds. Primary Care Medicine. Philadelphia, Pa: JB Lippincott Co; 1995:985-1004.
4.Brookhouser PE. Prevention of noise-induced hearing loss.
Prev Med.1994;23:665-669.Google Scholar 5.National Institutes of Health Consensus Development Panel. Noise and Hearing Loss: NIH Consensus Development Conference
Consensus Statement. Vol 8. Bethesda, Md: National Institutes of Health; January 22-24,
1990:3-5.
6.Leske MC. Prevalence estimates of communicative disorders in the U.S.: language,
hearing and vestibular disorders.
ASHA.1981;23:229-237.Google Scholar 7.National Center for Health Statistics. Plan, operation, and response results of a program of children's examinations.
Vital Health Stat 1.1967;No. 5. US Dept of Health, Education, and Welfare publication
PHS 1000.Google Scholar 8.National Center for Health Statistics. Hearing levels of youths 12-17 years: United States.
Vital Health Stat 11.1975;No. 145. US Dept of Health, Education, and Welfare publication
DHEW 75-1627.Google Scholar 9.Holmes AE, Kaplan HS, Phillips RM, Kemker FJ, Weber FT, Isart FA. Screening for hearing loss in adolescents.
Lang Speech Hear Serv Sch.1997;28:70-75.Google Scholar 10.Ezzati TM, Massey JT, Waksberg J, Chu A, Maurer KR.for the National Center for Health Statistics. Sample design: Third National Health and Nutrition Examination Survey.
Vital Health Stat 2.1992;No. 113. US Dept of Health and Human Services publication PHS
92-1387.Google Scholar 11.National Center for Health Statistics. Plan and operation of the Third National Health and Nutrition Examination
Survey, 1988-94.
Vital Health Stat 1.1994;No. 32. US Dept of Health and Human Services publication PHS
94-1308.Google Scholar 12.National Center for Health Statistics. National Health and Nutrition Examination Survey III: Audiometry
and Tympanometry for Health Technicians' Manual. Rockville, Md: Westat Inc; 1988.
13.National Center for Health Statistics. NHANES III Reference Manuals and Reports. Hyattsville, Md: Centers for Disease Control and Prevention; 1996.
14.Johnson C. NHANES III Analytic and Reporting Guidelines. Rockville, Md: National Center for Health Statistics; 1994.
15.Hanner P, Axelsson A. Acute acoustic trauma.
Scand Audiol.1988;17:57-63.Google Scholar 16.Brookhouser PE, Worthington DW, Kelly WJ. Noise-induced hearing loss in children.
Laryngoscope.1992;102:645-655.Google Scholar 17.Goodman A. Reference zero levels for pure-tone audiometer.
ASHA.1965;7:262-263.Google Scholar 18.SAS Institute Inc. SAS Language: Version 6. Cary, NC: SAS Institute Inc; 1990.
19.Shal BV, Barnwell BG, Hunt PN, Lavange LM. SUDAAN User's Manual, Release 5.50. Research Triangle Park, NC: Research Triangle Institute; 1991.
20.Veterans Administration. Rules and regulations.
52 Federal Register.44117-44118 (1987).Google Scholar 21.American Academy of Otolaryngology Committee on Hearing and Equilibrium,
American Council of Otolaryngology Committee on the Medical Aspects of Noise. Guide for the evaluation of hearing handicap.
JAMA.1979;241:2055-2059.Google Scholar 22.Rytzner B, Rytzner C. School children and noise.
Scand Audiol.1981;10:213-216.Google Scholar 23.Naeem Z, Newton V. Prevalence of sensorineural hearing loss in Asian children.
Br J Audiol.1996;30:332-339.Google Scholar 24.Cozad RL, Marston L, Joseph D. Some implications regarding high frequency hearing loss in school-age
children.
J Sch Health.1974;44:92-96.Google Scholar 25.Ries PW. Prevalence and characteristics of persons with hearing trouble: United
States, 1990-91.
Vital Health Stat 10.1994;No. 188:9-10.Google Scholar 26.Clark JG. Uses and abuses of hearing loss classification.
ASHA.July 1981;23:493-500.Google Scholar 27.Holmes AE, Kaplan HS, Nichols SW, Griffiths SK, Weber FT, Isart FA. Screening for hearing loss in juvenile detention centers.
J Am Acad Audiol.1996;7:332-338.Google Scholar 28.Anderson KL. Hearing conservation in the schools revisited.
Semin Hear.1991;12:340-364.Google Scholar 29.Klein JO. Epidemiology and natural history of otitis media. In: Bess FH, Hall JW, eds. Screening Children for Auditory
Function. Nashville, Tenn: Bill Wilkerson Center Press; 1992:31-38.
30.Barrett KA. Hearing and middle-ear screening of school age children. In: Katz J, Gabbay WL, Gold S, Medwetski L, Ruth R, eds. Handbook
of Clinical Audiology. 4th ed. Baltimore, Md: Williams & Wilkins;
1994:476-489.
31.Lee DJ, Gomez-Marin O, Lee HM. Prevalence of childhood hearing loss: The Hispanic Health and Nutrition
Examination Survey and the National Health and Nutrition Examination Survey
II.
Am J Epidemiol.1996;144:442-449.Google Scholar 32.Barone JA, Peters JM, Garabrant DH, Bernstein L, Krebsboch R. Smoking as a risk factor in noise-induced hearing loss.
J Occup Med.1987;29:741-745.Google Scholar