A unitary model of auditory frequency change perception

Area of Science:

• Auditory Perception
• Psychoacoustics
• Computational Auditory Neuroscience

Background:

• Frequency changes in sound are fundamental to understanding sound sources.
• Previous research often studied pitch and timbre independently, not their combined role in frequency change perception.
• A unified perceptual account for subjective judgments of frequency shifts is lacking.

Purpose of the Study:

• To propose and validate a unitary model for subjective judgments of "up" and "down" frequency changes.
• To investigate how spectral fine structure (SFS) and spectral envelope (SE) cues interact in auditory perception.
• To explore sound-specific and listener-specific factors influencing frequency change perception.

Main Methods:

• Generalized Shepard tones were used to manipulate SFS and SE cues independently and concurrently.
• Behavioral experiments collected listener judgments of "up" or "down" frequency shifts.
• A computational model was developed to fit behavioral data and analyze cue weighting.

Main Results:

• Subjective judgments followed the direction of the smallest log-frequency change for isolated SFS or SE shifts.
• Concurrent SFS and SE changes showed cue trade-offs, rarely resulting in a "both" percept, supporting a unitary percept.
• A computational model accurately predicted behavioral data, demonstrating adaptive cue combination.

Conclusions:

• Auditory perception integrates diverse cues for tracking frequency changes, forming a unitary percept.
• Cue weighting is adaptive, depending on sound characteristics (harmonic vs. inharmonic) and individual listener variability.
• This unified approach to frequency change perception parallels other basic auditory dimensions like spatial location.