| Summary: | 碩士 === 國立成功大學 === 資訊工程學系碩博士班 === 100 === Brain plasticity is the ability in brain to change its structure and function, and the major factor including experience and training. Musician’s brain received long-term musical training is also regarded as an ideal model to investigate plasticity of the human brain. Consonance of interval is a most significant general idea of western tonal music. Some studies indicated that cortical processing of musical consonance conforms to consonance of interval for amateur musicians. However, according to the psychoacoustic theory, consonance intervals are related to critical bandwidth (roughness). The consonant (perfect fifth) and dissonant (tritone) intervals include the existence of roughness (with and without roughness). Therefore, the research wants to find out the cortical processing of musical consonance and what are the differences with consonance of interval and roughness for musicians and non-musicians. The aim of the experiment is obtaining comparison of musicians and non-musicians by behavior and ERPs experiments. In the behavior experiment, amateur musicians accurately categorized the consonant and dissonant intervals (hit rate was 90%), but not for non-musicians (hit rate was 50%). Non-musicians considered that stimuli without roughness were consonant interval (percentage achieved 83%) and stimuli with roughness were dissonant interval (percentage achieved 79%).
In the ERPs analysis, N1 and P2 had significant response. N1 sources were in localized in the region of the primary auditory cortex. The amplitude of the N1 evoked by consonant or dissonant intervals had no significant difference from musicians or non-musicians. P2 sources were localized in the region of the secondary auditory cortex. Considering the consonance type, the P2 amplitude evoked by consonant intervals was stronger than by dissonant intervals from musicians. On the other hand, the P2 amplitude evoked by stimuli without roughness was stronger than by stimuli with roughness from non-musicians. According to the behavior and ERPs experiment, it took about 650 ms from receiving the stimuli to make the judgment for subjects, and musicians and non-musicians all had significant difference in P2 components (latency was 250 ms). Furthermore, ERPs results in P2 components were in agreement with the hit rate in behavior result for musicians and non-musicians, indicating the difference of consonance perception from musicians and non-musicians. The results point to the influence of expertise, since different ERPs were obtained cortical processing of listening to consonant and dissonant intervals. Musicians had enhanced in secondary auditory cortex compared with non-musicians and could accurately categorized the consonant and dissonant intervals, and non-musicians influenced by the existence of roughness while they categorized the stimulus. In conclusion, the perception of musical consonance in musicians and non-musicians reflects differently in cortical processing, resulting from whether received the musical training or not.
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