The role of temporal fine structure information for the low pitch of high-frequency complex tones

The fused low pitch evoked by complex tones containing only unresolved high-frequency components demonstrates the ability of the human auditory system to extract pitch using a temporal mechanism in the absence of spectral cues. However, the temporal features used by such a mechanism have been a matter of debate. For stimuli with components lying exclusively in high-frequency spectral regions, the slowly varying temporal envelope of sounds is often assumed to be the only information contained in auditory temporal representations, and it has remained controversial to what extent the fast amplitude fluctuations, or temporal fine structure (TFS), of the conveyed signal can be processed. Using a pitch matching paradigm, the present study found that the low pitch of inharmonic transposed tones with unresolved components was consistent with the timing between the most prominent TFS maxima in their waveforms, rather than envelope maxima. Moreover, envelope cues did not take over as the absolute frequency or rank of the lowest component was raised and TFS cues thus became less effective. Instead, the low pitch became less salient. This suggests that complex pitch perception does not rely on envelope coding as such, and that TFS representation might persist at higher frequencies than previously thought.