Eeg-based Sound Perception

As a universal and specific trait of humans, music played a key and particular role in human society. However, little has been understood by us regarding this oldest and most basic socio-cognitive phenomenon It is rational to use music as a tool combined with the domains of physiology, psychology, neuroscience and signal processing methods to investigate the underlying brain mechanisms of music perception, as it is helpful not only to reveal the musical ability of human, but also to understand the workings of the human brain.Timbre, a key and the most complex attribute of music, allows one to distinguish among tones which have the same pitch loudness and duration. Here, we present mismatch negativity (MMN) of the event-related brain potential (ERP) obtained from sixteen healthy individuals while they listened to complex instrumental tones and simple sine wave tones to research the timbre perception in humans and reach the following conclusion:Firstly, we find that the amplitude of P2 has showed a positive correlation to complexity of spectra, as we observed P2 were enhanced while responding to instrumental tones relative since wave tones.Secondly, in the experiment the mismatch negativity (MMN), generated by the brain's preattentive detection of a sound change, was elicited by an irregular timbre tone succeeding a regular timbre, demonstrating that timbre is preattentively processing in auditory sensor memory.Furthermore, using a condition controlling for refractoriness effects, we disentangle the N1, which has an early contribution to MMN, and the genuine MMN. The genuine MMN reflects the outcome of a memory comparison between neural models of the frequently presented standard sound with the sensory memory representation of the changed sound.In the meantime, we applied an electrical brain imaging approach using low-resolution electromagnetic tomography (LORETA) to estimate the neural sources of MMN responses in both traditional experimental paradigm and optimized one. Inverse modeling revealed sources for N1 and MMN in the prefrontal cortex, but in different position. These EEG results suggest N1 and MMN are spatially distinct activities.Lastly, the LORETA exposed a considerably stronger difference of the right relative to the left prefrontal region in timbre relative to preattentive perception during the optimized experimental paradigm, which provides evidence that the right lobe is particularly essential for analysis of temporal and spectral information involved in musical timbre.