Effects of Partial Hamming Function Modulation of Tone Bursts

Some perceptual effects of Hamming function modulation of pure-tone bursts of short duration were presented at an earlier ASA meeting [Spring 1967]. In the present studies, subjects' pitch percepts were measured and thresholds were obtained for tone bursts having contours of the following descriptions: (1) full Hamming function modulation; (2) full rectangular function modulation; (3) first half—Hamming function modulation, last half—rectangular function modulation; and (4) first half—rectangular function modulation, last half—Hamming function modulation. The full-cycle Hamming function bursts provided the least variance in pitch perception measurements and the highest thresholds. The rectangularly modulated tone bursts afforded the greatest variances in pitch measurements and the lowest thresholds. The effect to tone bursts having contours beginning as Hamming functions and ending as rectangular functions approached those of the full Hamming function modulations, whereas the effects to the tone bursts having contours beginning as rectangular functions and ending as Hamming functions approached those of the rectangular bursts. On the basis of preliminary data from hearing-impaired patients, clinical implications are cited relative to the threshold shifts obtained with Hamming function bursts as a function of burst duration and of tone frequency.