**6. Brain responses toward vocal expression in clinical populations**

The study on vocal emotion decoding in normal populations has provided a wide range of neurophysiological markers and experimental paradigms to examine how such process is impaired in a clinical context. Studies have been focusing on psychiatric‐risk populations and neurodevelopment disorders.

A study used an oddball paradigm in which a group of healthy listeners with anxious and depressive tendencies and a group of controls detected the target of emotional stimuli from a sequence of neutral expressions [30]. The emotional expressions were presented in voice, in face, or in voice‐face pair with congruent expressions. The amplitude of P3b in response to the deviant expression was reduced in the clinical group than the control group, only in voice‐face presentation. This finding suggests the crossmodal design as an effective approach to increase the sensitivity of the P300 amplitude difference between healthy populations and those with clinical symptoms.

Another study used an auditory oddball paradigm in which anger or happy deviant vocal or nonvocal synthesized syllables (data) were presented in a sequence of neutral syllables to listeners with symptoms in schizophrenia and normal listeners [31]. A larger mismatch of negativity was elicited following the deviant angry voice and anger‐bearing nonvocal sounds and such enlargement was decreased in those with schizophrenia. The weaker the MMN amplitudes, the more positive symptoms of schizophrenia. Using MMN responses to anger voice, anger‐derived nonvocal sound could predict whether someone received a clinical diagnosis of schizophrenia. These findings implicate that the emotional salience detection of voices differentiate the negative and positive symptoms in neuropsychiatric disorders at the preattentive level.

The emotional prosody was also examined in those with congenital amusia (a specific neu‐ rodevelopmental disorder featured as tone‐deafness, [32]). Lu et al. [32] presented emotional words spoken with declarative or the question voice to the amusics and their healthy control. The N1 was reduced and the N2 was increased in incongruent voice. The modulation of N1 was intact whereas the change in N2 was reduced in amusics, suggesting an impaired conflict processing in amusia. The authors argued that the impaired discrimination of speech intona‐ tion among amusic individuals may arise from an inability to access information extracted at early processing stages.
