### ASA 127th Meeting M.I.T. 1994 June 6-10

## 4aPP17. Interaction of three different types of maskers.

**Walt Jesteadt
**
Christina J. Kessler

Donna L. Neff

**
**
*Boys Town Natl. Res. Hospital, 555 N. 30th Street, Omaha, NE 68131
*

*
*
Models of additivity of masking typically assume that the same compressive
nonlinear transformation is applied to all individual masking effects before
they combine. The results for combinations of three different types of maskers
are not easily predicted, however, if some pairwise combinations of maskers
show more compressive effects than others. To explore this question, adaptive
thresholds were obtained for a 24-ms, 1600-Hz signal in the presence of three
different maskers presented alone and in various combinations: (1) a 400-ms
broadband noise simultaneous masker; (2) a 400-ms octave-band noise
simultaneous masker centered at 500 Hz, and (3) a 296-ms, 1600-Hz forward
masker with a 4-ms signal delay. The broadband noise was presented at 10 dB No;
the other two maskers were presented at seven levels that produced a range of
masked thresholds 15 dB above and below that for the broadband noise. Results
will be discussed in terms of an associative model in which the effects of two
maskers combine and the pairwise effect then combines with the third masker.
This model could be applied to data for listeners with sensorineural hearing
loss, where the hearing loss is treated as a masking effect. [Work supported by
NIDCD.]