Specifically, the SACF peaks can be described as bounded perturbations of the peaks of a reference harmonic signal. It is shown that the stimuli giving rise to each of these phenomena have a common structure. II A, the two psychoacoustic phenomena that drive this investigation are reviewed: noise edge pitch (NEP) and the pitch of a nearly harmonic complex with a single mistuned component. Such models and their many variants are capable of predicting a wide range of pitch phenomena and accord well conceptually with physiological observations at the level of the auditory nerve ( Cariani and Delgutte, 1996). In this formulation, pitch can be viewed as equivalent to the dominant periodicity of a signal after peripheral filtering. The pitch is then estimated by finding the delay time associated with the first large peak after the zero-delay. It consists of the following steps: passing an input signal through a cochlear filter bank, subjecting the output of each channel to a rectifying nonlinearity, then autocorrelating each channel to produce phase-alignment, and summing the resulting autocorrelation functions (ACFs) to produce a summary autocorrelation function (SACF). Having its roots in the work of Licklider (1951), the modern form of this approach was codified by Meddis and Hewitt (1991a, b). The autocorrelation (AC) model is the most widely accepted instantiation of the temporal theory of pitch perception. A possible physiological mechanism that could induce such peak shifting is discussed, and the model is tested against existing psychophysical data. This effectively shifts the peak location slightly for non-harmonic stimuli. The multiple-peak framework is extended with a non-standard peak-selection method that associates a delay time to a given peak in a manner that takes into account the entire shape of the bump surrounding the peak. A functional model is developed that can predict both of these pitch phenomena. This enables prediction of the NEP but suppresses the shift associated with a mistuned harmonic. Hartmann, Cariani, and Colburn recently proposed the use of multiple SACF peaks in the estimation process. Two examples are noise edge pitch (NEP) and the pitch induced by the mistuning of a single component of an otherwise harmonic stimulus. There are, however, a number of cases where the approach fails. Models based on this theory are capable of predicting a wide range of pitch phenomena. The standard autocorrelation model of pitch perception posits that the pitch of a stimulus can be predicted from the first major peak of a summary autocorrelation function (SACF) after the zero-delay peak.
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