On the origin of the stretched melodic octave
William M. Hartmann · The Journal of the Acoustical Society of America · 1991
It is well known that the psychological octave is stretched with respect to the physical octave, i.e., when listeners choose or adjust a melodic octave, the frequency ratio turns out to be greater than 2 to 1. Two explanations have been advanced to explain this effect. Terhardt [J. Acoust. Soc. Am. 55, 1061–1069 (1974)] suggested that the stretched melodic octave is learned from a harmonic octave that is stretched by partial masking of excitation patterns. The origin of the stretched melodic octave is therefore in the central nervous system. However, Ohgushi [J. Acoust. Soc. Am. 73, 1694–1700 (1983)] argued that the stretched melodic octave may be caused by the refractory delay in primary auditory neurons, as observed in electrophysiological single unit recordings. In his model, pitch is determined by the first several peaks in the interspike interval histogram, which are increasingly delayed for higher frequencies. The origin of the stretched melodic octave is therefore in the peripheral nervous system. The present paper shows that one can choose between central and peripheral models by an octave-judgment experiment that does not involve any pitch information in the auditory periphery. This is done by creating central pitch sensations with the Huggins effect. Data obtained from 2AFC constant-stimuli experiments favor the central-origin explanation of the stretched melodic octave. [Work supported by the NIDCD of the National Institutes of Health.]