Global processing of spectrally complex sounds in macaques (Macaca mullata) and humans

Area of Science:

• Comparative psychology
• Auditory neuroscience
• Sensory perception

Background:

• Understanding nonhuman perception is crucial for validating animal models of human sensory function.
• While human and animal frequency discrimination is studied, less is known about complex sound pattern perception differences.
• Previous research indicates most animals, including monkeys, are less adept than humans at discriminating pure tone frequencies.

Purpose of the Study:

• To compare the auditory perception capabilities of macaques and humans in discriminating complex sound patterns.
• To investigate species-specific differences in processing spectrally complex auditory information.
• To assess spectral-contrast sensitivity in primates using sine-modulated power spectra.

Main Methods:

• Measured spectral-contrast sensitivity in macaques and humans.
• Utilized stimuli with sine-modulated power spectra, analogous to visual sine-wave gratings.
• Tested performance across a sine-profile frequency range of 0.5–2.0 cycles/octave.

Main Results:

• Macaque auditory systems demonstrated significantly lower sensitivity compared to human systems within the tested frequency range.
• Rhesus macaques perceive spectrally complex sounds with less fidelity than humans.
• Substantial interspecies differences were observed in the processing of low-resolution spectral patterns.

Conclusions:

• The macaque auditory system exhibits reduced sensitivity to complex sound patterns compared to humans.
• Findings challenge traditional peripheral filter models, suggesting a central frequency integration process underlies these perceptual differences.
• Significant variations in central auditory processing exist across primate species, impacting complex sound discrimination.