Relative pitch representations and invariance to timbre

Area of Science:

• Psychoacoustics
• Auditory Perception
• Music Cognition

Background:

• Relative pitch perception is crucial for understanding speech and music.
• Timbre and fundamental frequency (f0) are key acoustic features influencing pitch perception.
• Existing research suggests pitch perception may be invariant to timbre under certain conditions.

Purpose of the Study:

• To investigate the impact of timbral differences on relative pitch judgments.
• To determine if timbre invariance in pitch perception depends on the processing of constituent frequencies versus f0.
• To examine pitch perception with harmonic and inharmonic sounds, which vary in f0 clarity.

Main Methods:

• Listeners performed pitch discrimination tasks (up/down, interval) using pairs of sounds.
• Stimuli included spoken vowels, instrument notes, and synthetic tones (harmonic/inharmonic).
• Timbral variations were systematically manipulated, and judgments were analyzed for accuracy and bias.

Main Results:

• Pitch judgment accuracy decreased when sounds had different timbres compared to identical timbres.
• Timbral differences introduced biases in pitch judgments, irrespective of whether sounds were harmonic or inharmonic.
• This timbre-induced bias persisted even when listeners processed f0 information from harmonic sounds.

Conclusions:

• Relative pitch perception is demonstrably not invariant to timbre, even with naturalistic timbral variations.
• Timbre influences pitch judgments regardless of whether they are based on spectral components or f0 estimations.
• The findings challenge assumptions of timbre invariance in auditory pitch processing.