Failure to hear binaural beats below threshold

The ability to hear binaural beats at 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 to the other ear. The tones at the two ears differed in frequency by 1, 3, or 6 Hz in different experiments. A two-alternative, forced-choice test was used to measure the listener's ability to detect the beats. Special care was taken to avoid a potential pitch cue. There was no evidence to suggest that binaural beats were detectable when the intensity of the variable-level tone was below 0 dB SL.