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

3pPP2. Failure to hear binaural beats below threshold.

Xiang Gu

Beverly A. Wright

David M. Green

Psychoacoust. Lab., Psychology Dept., Univ. of Florida, Gainesville, FL 32611

The ability to hear binaural beats at 200 and 500 Hz was assessed using a tone presented at 20 dB SL to one ear and a tone presented at a variable level ranging from -20 to 20 dB SL in steps of 10 dB to the other ear. A two-alternative forced-choice test was used to measure the listener's ability to detect the beats. In the ``beating'' interval, the frequencies of the tones at the two ears differed by 6 Hz. In the ``nonbeating'' interval, the tones at the two ears had the same frequency. Special care was taken to avoid a potential pitch cue by randomly presenting one of four paired frequencies to the two ears. The experiment was conducted in ``burst'' and ``fringed'' condition. There was no evidence to suggest that binaural beats were detectable when the intensity of the variable-level tone was below 0 dB SL. These data fail to replicate a result reported by Groen [Acta Oto-Laryngol. 57, 224--230 (1964)]. [Work supported by NIH.]