Intensity discrimination of brief Gaussian-windowed tones by hearing-impaired listeners

Abstract

For normal listeners, intensity DLs for Gaussian-shaped tone pulses are largest at medium pulse durations when the pedestals are 10 dB above threshold, either in quiet or in a pink-noise background. One explanation is that worst performance occurs when the internal representation is most compact in time and frequency, affording minimal opportunity for multiple looks [N. H. van Schijndel, T. Houtgast, and J. Festen, J. Acoust. Soc. Am. 105, 3425–3435 (1999)]. However, the mid-duration worsening is largest for medium overall levels, suggesting an involvement of the compression on the basilar membrane (BM), which is also greatest at medium levels [T. Baer, B. C. J. Moore, and B. R. Glasberg, J. Acoust. Soc. Am. 106, 1907–1916 (1999)]. If so, the mid-duration worsening should be reduced when BM compression is reduced by outer hair cell damage. To test this, subjects with sensorineural losses were tested using 1-kHz or 4-kHz pulses, in quiet or in pink noise that raised thresholds by 10–20 dB. For subjects with mild losses, poorest performance was sometimes found for medium durations. For more severe losses, intensity DLs tended to improve monotonically or remain roughly constant with increasing duration. The results provide support for both multiple-look and BM-compression explanations. [Work supported by MRC.]