A Study On Speech Prosody Cognition Of Tibetan Lhasa Dialect Based On ERP

This study will use ERP method and passive Oddball paradigm to analysis the amplitude and latency of mismatch negativity(MMN)which induced by the different types of stimulation of Tibetan Lhasa dialect in the cognitive processing of speech prosody information.We aimed to investigate the neural mechanism of automatic processing for brain to tone(55 tone and 53 tone,13 tone and 114 tone),intonation(statement,question,exclamation),stress(non-stress,first syllable stress,second syllable stress,Last syllable stress)in the preattention stage.Moreover,LORETA is used to locate the activation area of brain processing according to the activity of the dipole.Three groups of independent experiments were designed(the single syllable-tone change,the double syllable-intonation change,the three syllable-stress change)in this study.And the stimuli in each experiment were different from the fundamental frequency FO.The results showed:(1)In the 3 groups,the ERP induced by the deviant stimuli was significantly negative than the standard stimulus,indicating that the brain can automatically perceive the phonological differences in the speech prosody of the Lhasa dialect in the pre attention stage;(2)In the pre attention stage,tone processing showed a left hemisphere advantage,mainly in the left hemisphere temporal gyrus.The results show that the tone processing of Tibetan Lhasa dialect is the same as that of Chinese.Although the minimal opposition of tone is relatively less,it can be proved from the cognitive point of view that the Tibetan Lhasa dialect belongs to a tonal language;(3)In the pre attention stage,intonation processing showed a right hemisphere advantage,significant activation in the gyri centralis anterior;Stress processing showed a right hemisphere dominance and significant activation in the posterior cingulate gyrus in the perception process of speech prosody in Tibetan Lhasa dialect.The processing of intonation and stress shows that in Lhasa dialect,intonation and stress are not semantically distinct,which is a kind of paralanguage information.Therefore,the processing of intonation and stress is similar to that of melodic processing.(4)The experimental results support that the hemispheric dominance of prosodic information processing depends on the pitch itself.