Da. Nelson et Ac. Schroder, RELEASE FROM UPWARD SPREAD OF MASKING IN REGIONS OF HIGH-FREQUENCY HEARING-LOSS, The Journal of the Acoustical Society of America, 100(4), 1996, pp. 2266-2277
The upward spread of masking was compared for 500-Hz quasifrequency-mo
dulated (QFM) and sinusoidally amplitude-modulated (SAM) maskers. The
modulation rate was 20 Hz. These maskers had identical magnitude spect
ra but different envelopes, which were relatively flat for the QFM mas
ker and strongly fluctuating for the SAM masker. At signal frequencies
more than an octave above the masker, masked thresholds for the SAM m
asker were lower than for the QFM masker, revealing ''masking release'
' (QFM-SAM masked threshold differences) exceeding 30 dB in normal-hea
ring ears. In ears with high-frequency sensorineural hearing loss, but
normal hearing in the region of the masker, masking release was marke
dly reduced or completely absent in regions of hearing loss. The data
were evaluated with a model of masking based on the linearized respons
e growth (LRG) of basilar membrane transfer functions associated with
cochlear damage in animals. The LRG model predicted more gradual slope
s of the growth of masking and reduced amount of masking in regions of
hearing loss. The reduced masking release seen in regions of hearing
loss could be largely accounted for by a more rapid growth of response
to the probe tone in regions of hearing loss. (C) 1996 Acoustical Soc
iety of America.