The auditory ‘C-process’: analyzing the spectral envelope of complex sounds

摘要: Abstract Objective : To examine the hypothesis that auditory evoked potentials (AEPs) to pitch and timbre change of complex harmonic tones reflect a process spectral envelope analysis. Methods AEPs were recorded to: (1) continuous ‘clarinet' whose abruptly rose or fell by 1 7 semitones every 0.5 1.5 s; (2) cycle 6 pitches changing (3) constant (spectral shape) changed periodically; (4) high- low-pass filtered tones. Results The amplitudes ‘change-N1' (CN1) potential peaking at ca. 90 ms following CP2 influenced far greater degree time interval between changes, than magnitude occurrences same pitch. Amplitudes also strongly dependent on number partials present, irrespective whether they increasing decreasing in energy. algebraic sum responses closely approximated response unfiltered tone. Conclusion rate-sensitivity cannot be explained refractoriness frequency-specific ‘feature detector' neurones, but rather (termed ‘C-process') which analyzes amplitude modulations across envelope, contribution different frequency bands combining linearly scalp-recorded activity. On-going computation shape may an important factor maintaining perceptual constancy timbre.