Aging and the 4-kHz air-bone gap.
OBJECTIVE
In this study, the authors assessed age- and sex-related patterns in the prevalence and 10-year incidence of 4-kHz air-bone gaps and associated factors.


METHODS
Data were obtained as part of the longitudinal, population-based Epidemiology of Hearing Loss Study (Cruickshanks et al., 1998). An air-bone gap at 4 kHz was defined as an air-conduction threshold ≥ 15 dB higher than the bone-conduction threshold in the right ear.


RESULTS
Among 3,553 participants ages 48-92 years at baseline (1993-1995), 3.4% had a 4-kHz air-bone gap in the right ear. The prevalence increased with age. Among the 120 participants with an air-bone gap, 60.0% did not have a flat tympanogram or an air-bone gap at 0.5 kHz. Ten years later, the authors assessed 2,093 participants who did not have a 4-kHz air-bone gap at baseline; 9.2% had developed a 4-kHz air-bone gap in the right ear. The incidence increased with age. Among the 192 participants who had developed an air-bone gap, 60.9% did not have a flat tympanogram or air-bone gaps at other frequencies.


CONCLUSIONS
These results suggest that a finding of a 4-kHz air-bone gap may reflect a combination of aging and other factors and not necessarily exclusively abnormal middle-ear function.
University of Wisconsin-Madison, Wisconsin, USA. nondahl@episense.wisc.edu
David M
DM
Nondahl
Ted S
TS
Tweed
Karen J
KJ
Cruickshanks
Terry L
TL
Wiley
Dayna S
DS
Dalton
D000158:Acoustic Impedance Tests; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000388:Air; D001844:Bone Conduction / Q000502:physiology*; D004424:Ear Canal / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006314:Hearing Loss, Conductive / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors