Abstract
The periodicity pitch sensation is predicted to be in close correlation with the envelope time pattern of the complex tone from the Schonten's experiment on "residue", together with the duplex theory proposed by Licklider. The pitch of the unharmonic tones was determined by the pitch matching method simultaneously with the measurement of the time pattern of the periodicity of the envelope of complex tones. The values of the pitch measured were found to coincide with the frequencies determined from the periods of the envelopes. The unharmonic tones examined in this experiment were produced by shifting the spectral components of harmonic tones by Δ Fc/s on the frequency scale. The signals before being shifted were approximately the periodic damped waves, and were also the "output" of the resonance circuit driven by the periodic pulses. If it is assumed that the time pattern of the envelope is reserved in the signal traveling through the nerves, the result of this experiment may be explained by the duplex theory. The next experiment concerned with the frequency response of the periodicity pitch sensation. The complex tones examined had the clearly determined time pattern corresponding to the fundamental frequency but had not the frequency components under 1200 c/s. The result shows that the percentage score of the pitch perception to the fundamental frequency decreases as the frequency is increased higher, e. g. 75% at 300 c/s, 50% at 500 c/s. This result suggests that a filtering action exists in the circuit determining the periodicity pitch with the time pattern in the ear. These experiments seem to be useful for designing the pitch extracter from the vowels and also for composing the hearing theory.
