Neurophysiological time course of timbre-induced music-like perception

Area of Science:

• Neuroscience
• Auditory Perception
• Music Cognition

Background:

• Traditionally, pitch variation is considered essential for musical identity.
• Previous research indicates a right-lateralized hierarchical shift in auditory processing for sounds of varying pitch complexity.

Purpose of the Study:

• To investigate if musical perception driven by timbre irregularities, without pitch changes, elicits a similar hierarchical neural processing profile.
• To determine if the neural code for musicality is independent of pitch encoding.

Main Methods:

• Electroencephalography (EEG) was used to record brain activity in subjects listening to pitchless sound streams.
• Sound streams varied in timbre (white, pink, brown noise) and were presented in musical and nonmusical arrangements.
• Subjects classified the sound streams as musical or nonmusical.

Main Results:

• Musical processing of timbre-irregular, pitchless sounds showed right-dominant alpha (α) power enhancement.
• A lateralized increase in theta (θ) phase-locking and spectral power was observed, indicating higher-level auditory processing.
• Theta phase-locking was more pronounced in musicians than non-musicians.

Conclusions:

• Musicality can be induced by timbre irregularities alone, independent of pitch encoding.
• The findings support a hierarchical neural processing shift similar to that observed with pitched melodies.
• Results have implications for understanding music processing in individuals with pitch perception deficits.