Mr. Leek et V. Summers, AUDITORY FILTER SHAPES OF NORMAL-HEARING AND HEARING-IMPAIRED LISTENERS IN CONTINUOUS BROAD-BAND NOISE, The Journal of the Acoustical Society of America, 94(6), 1993, pp. 3127-3137
Listeners with sensorineural hearing impairment typically exhibit audi
tory processing deficits such as reduced frequency and/or temporal res
olution. Such deficits may represent separate sequela of auditory path
ology or may result directly from the sensitivity loss and the require
ment to listen at high levels. To assess the impact of increased thres
holds on frequency resolution, auditory filter characteristics were de
termined for hearing-impaired and normal-hearing listeners at 500 and
2000 Hz in the presence of continuous broadband noise meant as a rough
simulation of hearing loss. In the fitting procedure, the low-frequen
cy skirt of the derived auditory filter was allowed to vary as a funct
ion of signal level, permitting different filter shapes to be estimate
d at high versus low signal levels. Listeners with moderate hearing lo
sses at 2000 Hz demonstrated near-normal auditory filter shapes for lo
wer signal levels, but increasingly broad and asymmetric filters as si
gnal level was raised. At 500 Hz, where hearing losses were mild, filt
er bandwidths increased little at the higher signal levels. The presen
ce of broadband noise had essentially no effect on filter shapes of ei
ther listener group. The filter shape abnormalities demonstrated by li
steners with moderate hearing loss, which were not observed in normal-
hearing listeners at the same signal levels, indicate that poor freque
ncy resolution in these patients for high-intensity stimuli does not f
ollow directly from decreased sensitivity, but instead reflects an ind
ependent pathology.