ASA 124th Meeting New Orleans 1992 October

1pPP5. Directional masking of a complex signal by speech spectrum noise.

Kim Abouchacra

Tomasz Letowski

Dept. of Commun. Disord., Penn State Univ., 5 Moore Bldg., University Park, PA 16802

An experiment was conducted to investigate the effects of spatial separation of speakers on the detectability of a complex stimulus in speech spectrum noise (65 dB SPL). Twenty normal hearing subjects were randomly assigned into groups of 10 subjects each. Detection thresholds were obtained using the Bekesy up-and-down tracking technique and an ascending technique for the first and second group, respectively. At five different combinations of azimuth of the signal and noise sources, six thresholds were obtained for each subject. The results showed that detectability of a signal in noise depends on the relative spatial location of both the signal and noise source. A secondary objective of the experiment was to determine if knowledge of the source locations improves a listener's detection threshold. A light display was used to indicate the source locations. No difference in detection thresholds was seen for either group in any sound source combination when compared to conditions without a light display.