Prevalence of hearing impairment in a rural midwestern cohort: estimates from the Keokuk county rural health study, 1994 to 1998.
OBJECTIVE
The current paper estimates the prevalence of hearing problems in a rural population, analyzes the prevalence of hearing problems across age groups, and compares the prevalence of hearing problems in this population with results obtained in other populations.


METHODS
Data were obtained from a random sample of the residents of a rural county, stratified by farm, rural non-farm, and town residence. Hearing test results were obtained from participants between the ages of 8 and 92 years (N = 1972; 47% male). Pure-tone thresholds were classified as normal or impaired using a number of metrics, including speech intelligibility index values. Selected comparisons of crude rates were made with previous population-based studies of hearing loss prevalence.


RESULTS
Nearly all (99%) of the participants in this study had significant hearing impairment. Atypical hearing impairment is most prevalent at 6 kHz. In males, this excess impairment shifts to lower frequencies with age but monotonically decreases in females. Notched configurations were most common among those between 30 and 59 years old. In females, the prevalence of hearing impairments sufficient to interfere with speech understanding begins to rapidly increase in the 6th decade (4th decade in males). Comparisons with prior population-based studies in the United States and Great Britain identified few significant differences.


CONCLUSIONS
Significant hearing impairment is common in rural populations. The high prevalence in this population is similar to that found in other population-based studies. Future studies are needed to examine (1) the risk factors for hearing impairment, (2) the natural course of hearing problems across the life span, and (3) the effect of programs for the prevention of hearing impairment and rehabilitation for persons with existing hearing impairments.
Flamme
Gregory A
GA
Department of Speech Pathology and Audiology, University of Iowa, Iowa City, Iowa, USA.
Mudipalli
V Ranjit
VR
Reynolds
Stephen J
SJ
Kelly
Kevin M
KM
Stromquist
Ann M
AM
Zwerling
Craig
C
Burmeister
Leon F
LF
Peng
Shu-Chen
SC
Merchant
James A
JA
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D002648:Child; D015331:Cohort Studies; D005260:Female; D006306:Health Surveys; D034381:Hearing Loss / Q000453:epidemiology*; D006801:Humans; D007484:Iowa / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012424:Rural Population / Q000706:statistics & numerical data*; D017678:Sex Distribution; D013067:Speech Perception