Voice selectivity in the temporal voice area despite matched low-level acoustic cues

Area of Science:

• Neuroscience
• Auditory Perception
• Human Brain Imaging

Background:

• Temporal voice areas (TVAs) in the superior temporal gyrus and sulcus respond preferentially to vocal sounds.
• Previous interpretations suggested TVA selectivity might be due to low-level acoustic cues like harmonic content or spectrotemporal complexity.

Purpose of the Study:

• To investigate whether the right temporal voice area (TVA) remains selective for human voices when acoustic cues are controlled.
• To determine if simple acoustic features can explain voice selectivity in the TVAs.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Single vowel stimuli were contrasted with musical instrument notes matched for harmonic-to-noise ratios and pitches.
• Auditory chimeras, preserving subsets of vocal sound acoustic features, were employed.

Main Results:

• The right TVA showed preferential activation for natural human voices compared to control sounds.
• TVAs did not show increased activation for artificial chimeras that mimicked vocal spectral profiles.
• Acoustic measures like temporal modulations and spectral complexity did not account for the observed voice selectivity.

Conclusions:

• Simple acoustic cues are insufficient to explain voice selectivity in the temporal voice areas (TVAs).
• The right TVA's preference for human voices suggests a more sophisticated neural mechanism for voice processing.