Auditory Masking by Multiple Tones
Gerald C. O'Leary · The Journal of the Acoustical Society of America · 1963
The masking of a single sinusoid by two other pure tones was measured monaurally by the Békésy technique. The maskee was pulsed slowly at the rate of one pulse per second. The maskers were on continuously. Ten pairs of maskers were chosen to cover the range 300 to 2300 cycles. The masking was measured two ways: (1) as a function of the frequency of the maskee, holding the frequency and level of the maskers constant; and (2) as a function of the frequencies and levels of the maskers holding the frequency of the maskee constant. Data from four subjects were obtained. An empirical model for describing the masking function is presented. In an effort to link the masking effect to speech perception, the experiment was extended to consider the masking of one spectral line by all other frequency components in a synthetic speech sound. A vowel synthesizer was arranged with a phase-locked frequency divider so that a prescribed spectral line could be controlled in amplitude and phase. Intensity limens for individual components located at formant peaks and in valleys between formants were determined. These data are described for three vowel sounds and are related to the two-tone masking model.