The Yost approach to pitch perception: What we can learn from noise-like stimuli

One of Bill's major contributions to psychoacoustics is his innovative work using rippled noise (RN) to understand pitch. Bill has argued that RN-pitch percepts can be accounted for by models based on autocorrelation. Working with Bill, we showed that behavioral responses obtained from chinchillas to RNs generally paralleled those obtained from humans, suggesting the underlying processing is similar between the two species. Recent work from my lab using noise-vocoded harmonic tone complexes (NV-HTCs) was inspired by Bill's approach with RNs. NV-HTCs can also evoke pitch percepts like RNs, but present a challenge to Bill's autocorrelation approach, because they can have strong harmonic structures with weak or no periodicities. However, when NV-HTCs are passed through a gammatone filterbank model, weak stimulus periodicities become augmented in summary correlograms. An analytical model based on summary correlograms for NV-HTC responses from (1) humans in a magnitude estimation task and (2) chinchillas in a stimulus generalization task suggests that the underlying processing does indeed differ between the two species. Specifically, chinchillas appear to process the envelope whereas humans appear to process the fine structure. This talk will explore why this apparent processing difference exists, despite the similarity in chinchilla and human auditory filter bandwidths.