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

4pPP9. Discriminability of three-tone, common envelope signals.

Depts. of Electr. Eng. & Speech and Hear. Sci., Ohio State Univ., Columbus, OH 43210

The IWAIF model [Anantharaman et al., J. Acoust. Soc. Am. 94, 723--729 (1993)] has been successfully used to explain the discriminability of two-tone complexes, called Voelcker pairs, which have the same envelope but differing fine structure [Feth et al., J. Acoust. Soc. Am. 72, 1403--1412 (1982)]. The addition of an equal amplitude third tone at the center frequency of the two-tone complex results in a three-tone complex pair which continue to have a common envelope. The IWAIF model predicts that the center tone acts as a masker, with the three-tone complex pairs being less discriminable than the corresponding two-tone complex pairs. Further the discriminability diminishes with increase in the level of the center tone. Thus to be equally discriminable, a larger frequency separation between the two extreme tones is needed for the three-tone pairs as compared to the corresponding two-tone complex. In this study the performance of listeners to such three-tone pairs at various center frequencies is investigated. The corresponding IWAIF predictions are compared with the subject data. [Work supported by AFOSR.]