Abstract
This study concerns the masking of binaural beats between a pure tone, stimulating one ear, of f0 + d frequency (d = 3 Hz) and the differential sound originated in the other ear by stimulation with the mixing of 2 pure tones of frequency f1, f2 (f2 – f1 = f0). The masking sound is a third-octave filtered white noise, of nominal frequency fn variable between 200 and 4000 Hz, and sound pressure also variable. For each fn and for each constant value of f0, f1, f2, the minimum sound pressure level of the narrow-band noises for masking the beat is measured as a function of the frequency fn; the sound pressure level of the pure tones is maintained constant at 45 dB. The minimum sound pressure level of the narrow-band noises for masking the normal beats (a pure tone of 315 Hz at the left ear, of 318 Hz at the right ear) is also determined. The latter measurement gives, as expected, a very deep minimum at 315 Hz; from the other measurements it results some oscillations of experimental values, with a mean value generally decreasing as the nominal frequency of the masking noise is increased. This phenomenon is discussed.