ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pPP36. Modeling loudness growth and loudness summation in hearing-impaired listeners.

S. Launer

V. Hohmann

B. Kollmeier

AG Med. Phys., FB8, Univ. Oldenburg, Postbox 2503, 26111 Oldenburg, Germany

The goal of this study is to model the effect of sensorineural hearing impairment on loudness perception for stationary stimuli of variable bandwidth. Loudness growth functions were obtained employing a categorical scaling technique with 10 categories. Loudness scaling was performed with 9 normal-hearing and 14 sensorineural hearing-impaired subjects employing bandfiltered noises with bandwidths between 1--6 critical bands. For normal-hearing listeners, categorical scaling revealed similar differences across stimulus conditions as with loudness balancing. The loudness functions of the hearing-impaired listeners show both, a steeper increase (recruitment) and reduced loudness summation. Both aspects were successfully modeled by Zwicker's loudness model with three extensions to take account of hearing impairment. Raised audiometric threshold is modeled by a frequency-dependent attenuation after calculation of excitation patterns. Increasing the exponent in calculating the specific loudness yields recruitment. Reduced frequency selectivity is accounted for by the normal dependence of filter bandwidth on level in the excitation patterns. The extended model describes well the measured individual loudness growth functions of hearing-impaired subjects for stimuli of differing bandwidth.