Perception of the missing fundamental in nonhuman primates

Area of Science:

• Auditory Neuroscience
• Psychoacoustics
• Animal Behavior

Background:

• Understanding pitch perception is crucial for neurophysiological studies.
• The 'missing fundamental' phenomenon, where pitch is perceived without the lowest harmonic, is a key area of auditory research.

Purpose of the Study:

• To investigate the ability of rhesus monkeys to perceive pitch in complex tones with and without their fundamental frequency.
• To establish behavioral paradigms for future neurophysiological experiments on pitch mechanisms.

Main Methods:

• Four rhesus monkeys were trained on a matching-to-sample task involving complex tones.
• Tones consisted of a five-component harmonic series; the first tone varied in the number of missing lower harmonics (0-3), while the second tone was complete.
• The fundamental frequency range tested was 200–600 Hz.

Main Results:

• Three monkeys successfully matched tones with missing fundamentals to complete harmonic complexes of the same perceived pitch.
• One monkey required the physical presence of the fundamental frequency to perform the task.
• The results indicate that most trained monkeys could perceive the pitch of the missing fundamental.

Conclusions:

• Rhesus monkeys can be trained to perceive pitch based on harmonic information, including the 'missing fundamental' phenomenon.
• This finding supports the idea that the auditory system can infer pitch from spectral cues.
• The trained monkeys provide a suitable model for investigating the neural basis of pitch perception.