Effect of Masking on the Pitch of Periodic Pulses

Abstract

The pulse‐train pitch‐matching experiments of Flanagan and Guttman have been extended to investigate the effect of selective masking on the pitch of these stimuli. For unmasked stimuli, at pulse repetition rates below approximately 150 pps, a pitch mode correlated with the pulse repetition rate is generally obtained; at fundamental frequencies higher than approximately 150 cps (and below 800 cps), a pitch mode correlated with the fundamental frequency is generally obtained even if the fundamental component has been rejected from the challenge stimulus by filtering. There is a transition region of repetition rates of the challenge stimulus in which the cues for both pitch modes are strongly competing. Present results indicate that if, to challenge stimuli in or near the transition region, high‐pass noise (1000‐cps cutoff) is added the “buzz” quality associated with the pulse‐rate mode can be masked and a fundamental‐frequency pitch judgment elicited. Conversely, low‐pass noise (1000‐cps cutoff) can mask the “tonal” quality associated with the fundamental‐frequency mode and elicit pulse‐rate pitch judgments. Narrow bands of noise or sinusoids are equally effective as maskers. Fundamental‐frequency pitch judgments and pulse‐rate pitch judgments are suppressed by narrow bands of noise or sinusoids centered at about 500 and 5000 cps, respectively. It is concluded that, for pulse‐train stimuli with repetition rates in or near the transition region, fundamental‐frequency and pulse‐rate pitch modes are associated with distinct auditory channels below 1000 and above 1000 cps, respectively, with special prominence to the regions near 500 and 5000 cps, respectively. It is further suggested that these results tend to support periodicity mechanisms for mediating these modes of pitch perception.