Da. Fabry et al., DO ADAPTIVE FREQUENCY-RESPONSE (AFR) HEARING-AIDS REDUCE UPWARD SPREAD OF MASKING, Journal of rehabilitation research and development, 30(3), 1993, pp. 318-325
Speech recognition scores in noise are improved for some subjects who
wear hearing aids that reduce low-frequency noise with an adjustable h
igh-pass filter circuit. To evaluate whether these improvements were r
elated to a reduction in upward spread of masking, pure-tone masking p
atterns for a low-frequency bandpass noise were measured in normal and
hearing-impaired subjects. The filter skirt of the noise masker was v
ery steep, with attenuation above the 1000 Hz cutoff greater than 120
dB per octave. Masking patterns for the same noise were also obtained
in the presence of a high-pass filter that simulated the effects of an
adaptive frequency response (AFR) hearing aid. Differences in the mas
king patterns were considered a measure of upward spread of masking. O
n average, subjects with high-frequency hearing loss demonstrated grea
ter amounts of upward spread of masking than did normal-hearing listen
ers. Further, monosyllabic speech recognition in noise testing indicat
ed improvements in performance of the hearing-impaired subjects relate
d to the decrease of upward spread of masking in the high-pass filteri
ng conditions.