The Low Pitch of High-Frequency Complex Tones Relies on Temporal Fine Structure Information

High-frequency complex tones containing only unresolved harmonic components with a frequency spacing Δf usually evoke a low pitch equal to Δf. However, for inharmonic components, the low pitch is often found to deviate slightly from Δf. Whether this pitch shift relies exclusively on temporal fine structure (TFS) cues has been a matter of debate. It is also controversial up to which frequency TFS information remains available, and to what extent envelope cues become dominant as frequency increases. Using a pitch-matching paradigm, this study investigated whether the pitch of transposed tones with unresolved inharmonic components is determined by (A) the time intervals between the most prominent TFS peaks in their waveform (multimodal distribution of matches around subharmonics of the carrier frequency fc), (B) the timing between peaks in their envelope (unimodal distribution of matches around the envelope rate fenv), or whether (C) no salient pitch is evoked (random matches). Six musically-trained normal-hearing subjects matched the fundamental pitch of a broadband pulse train to that of transposed tones with carrier frequencies fc = [3, 4, 5, 6, 7] kHz and envelope rates fenv = [fc/11.5, fc/14.5]. All stimuli were presented at 50 dB SPL in broadband pink-noise (13.5 dB/Hz at 1 kHz), and 40 matches per condition were obtained. For fenv = fc/11.5, the results favored hypothesis A for all values of fc, indicating that TFS cues are available and used for pitch extraction, up to at least 7 kHz in most subjects. For fenv = fc/14.5, hypothesis A was valid for values of fc up to 5 kHz, and the distribution of matches showed a higher variance indicating a less salient pitch. In other conditions, hypothesis C was valid, suggesting that envelope cues do not take over as TFS cues become unavailable. These results strongly suggest that the monaural representation of TFS persists at high frequencies and that pitch does not rely on envelope coding as such.