Dynamically varying timbre cues interfere with listeners’ pitch perception

One timbre cue that has been studied psychophysically is the spectral centroid of a steady-state harmonic complex, which corresponds to the “brightness” of the complex. Complexes having higher spectral centroids tend to be perceived as having higher pitches even with a constant fundamental frequency (F0). To further understand pitch-timbre interactions, the current study investigates whether dynamically varying spectral centroids of harmonic complexes affect the pitches. Normal-hearing listeners ranked the pitch of two harmonic complexes on each trial. In some trials the spectral centroid of one complex swept from low to high frequencies across its duration while the centroid of the other complex varied from high to low. Other trials had centroids moving from high to low then low to high across the interval. F0s of the two complexes differed by one just noticeable difference. Results show that a more recent rising spectral centroid tends to bias listeners to generate “higher pitch” responses, while a more recent declining spectral centroid tends to bias listeners to generate “lower pitch” responses, even when the rising and declining stimuli had identical long-term spectra. The results suggest that the spectral centroids at various temporal position of a harmonic complex do not influence pitch perception equally.