ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

2pPP6. Localizing broadband noise in a reverberation room.

Timothy J. VanderVelde

Millicent M. Ow

Wendy R. Thorpe

William Morris Hartmann

Brad Rakerd

Michigan State Univ., East Lansing, MI 48824

Sound localization experiments were performed to determine the relative importance of steady-state information and onset-transient information to the localization of broadband noise in a reverberant environment. Experiments used a source identification method with an array of 24 speakers, separated by 2 deg of azimuth, in a reverberation room (RT60(approximately equal to)4 s). Noise signal onsets were either abrupt, or slowly ramped, or entirely masked by other noise. The ratio of direct to reverberant sound was controlled by positioning the listener with respect to the speakers. Data showed that (1) localization of sound with abrupt onsets is particularly insensitive to direct/reverberant ratio. (2) Slowly ramped onsets allow listeners to use localization information in the weak direct sound before the reverberant field has fully formed. (3) Some listeners (all young) have remarkable ability to extract localization cues from apparently overwhelming reverberated noise when onsets are masked. Further experiments suggested that these listeners make use of cues at high frequencies where reverberated sound is minimized by wall absorption; performance for these listeners decreased dramatically when the noise was lowpassed at 5 kHz. [Work supported by the NIDCD.]