ASA 125th Meeting Ottawa 1993 May

2pPP11. A comparison of octave-band noise masking patterns obtained from normal-hearing and hearing-impaired listeners.

Christine M. Rankovic

Patrick M. Zurek

MIT, Res. Lab. of Electron., Rm. 36-749, Cambridge, MA 02139

In cases where spread of masking plays a role, interfering noise is more detrimental to speech reception for hearing-impaired than for normal-hearing listeners [e.g., Rankovic et al., J. Acoust. Soc. Am. 90, 2319 (A) (1991)]. To examine such effects, masking patterns for octave-band noises collected from 5 normal-hearing and 6 hearing-impaired subjects were compared. Maskers were centered on 0.5, 1.0, and 2.0 kHz and varied in overall level from 70 to 95 dB SPL in 5-dB steps and masked thresholds were measured with 1/3-octave resolution. The hearing-impaired subjects' masking patterns were compared with the averaged patterns of the normal-hearing subjects and the following were found: (1) a low-frequency spread-of-masking (for both normal and impaired listeners) that is roughly constant for the masker levels used here; (2) generally shallower slopes on the high-frequency side of masking patterns for impaired listeners; and (3) for some impaired listeners, substantially greater masking within the masker band. These results will be discussed in relation to the design of hearing aids that modify the frequency-gain characteristic with the goal of reducing upward spread of masking, and will be compared with the masking-pattern equations for impaired listeners proposed by Ludvigsen [C. Ludvigsen, J. Acoust. Soc. Am. 78, 1271--1280 (1985)]. [Work supported by NIH.]