Eeg-based Pitch Perception

Electroencephalogram (EEG) represents the general electrical activity of the whole brain, containing much neural information. Music has become a more and more effective tool for brain research during the past few years, of which pitch research is an fundamental part in brain mechanism exploration because of its substantial role in both language and music perception and recognition. In this work, we designed an experiment of music perception for different pitch level to collect EEG data. Then, the acquired data were analyzed by two methods (local and non-local) as follows:1. EEG data recorded when subjects were listening to two key-transposed music and the original music is analyzed by PSD (Power Spectral Density) , results show that: power ofθfrequency band has a close relation with changed direction of the listened music on the Cycle of fifths. For both key transposition and octave transposition, it increases with the psychological distance between transposed music and the original one. The right hemisphere EEGθpower is larger than that of the left; power ofα1 frequency band demonstrates similar trend as that ofθfrequency band, but the distribution area hemisphere predominance is different. Power ofα1 frequency band on the two hemispheres is almost equal; As forβ1 frequency band, only the key transposition take on distinct difference, mainly on frontal and temporal areas.2. A functional brain network is constructed using the EEG data when subjects listening to different pitch level music. Statistical characteristic of the resulting network including the distribution of degree, the clustering coefficient and the brain neural network information entropy are calculated. Results illustrate that no matter which pitch level music the brain is exposed, the brain demonstrates the characteristics of scale-free and small-world network. The important point to emphasize is that the clustering coefficient and the brain neural network information entropy is the largest when subjects are listening to the original music. It can be seen, in the condition of listening to original music, there is more nerve cell cluster together in the brain and the cerebra gained the most information.We can come to this conclusion that EEG data changes depending on the pitch level of perceived music. Especially the transposed music and the original one shows significant difference in PSD analysis of several frequency band as well as the clustering and information absorbability of the functional brain network. These two methods are both good for investigation of music perception of different pitch level.