Efficient codes for memory determine pitch representations

Abstract Perceptual systems have finite memory resources and must store incoming signals in compressed formats. To test whether representations of a sound’s pitch might derive from this need for compression, we compared discrimination of harmonic and inharmonic sounds across delays. In contrast to inharmonic spectra, harmonic spectra can be summarized, and thus compressed, using their fundamental frequency (f0). Despite being comparable for sounds presented back-to-back, discrimination was better for harmonic than inharmonic stimuli when sounds were separated in time, implicating memory representations unique to harmonic sounds. Patterns of individual differences indicated that listeners use different representations depending on the time delay between sounds, directly comparing the spectra of temporally adjacent sounds, but transitioning to comparing f0s across delays. The need to compress sound into memory appears to determine reliance on f0-based pitch, and may explain its importance in music, in which listeners must extract relationships between notes separated in time.