Abnormalities in auditory efferent activities in children with selective mutism

Area of Science:

• Auditory Neuroscience
• Psychiatry
• Speech Science

Background:

• Auditory efferent pathways, including the middle-ear acoustic reflex (MEAR) and medial olivocochlear bundle (MOCB) reflex, are hypothesized to monitor self-vocalization.
• Human studies on auditory efferent activity during self-vocalization are limited, with most research conducted in animal models.

Purpose of the Study:

• To investigate the role of auditory efferent activity in self-vocalization using children with selective mutism (SM) as a human model.
• To compare auditory efferent function in children with SM to that of typically developing children.

Main Methods:

• Assessed MEAR and MOCB function in 31 children with SM and 31 controls using acoustic reflex thresholds, decay functions, and transient-evoked otoacoustic emissions suppression.
• Evaluated auditory afferent function via auditory brainstem responses (ABR).
• All participants had normal hearing thresholds and tympanograms.

Main Results:

• A significantly higher proportion of children with SM exhibited abnormal MEAR (58.6%) and MOCB (38%) function compared to controls (9.7% and 8%, respectively).
• The overall prevalence of abnormal MEAR and/or MOCB function was significantly higher in the SM group (71%) versus controls (16%).
• Auditory afferent function, assessed by ABR, was normal in all children.

Conclusions:

• Aberrant efferent auditory function is prevalent in children with selective mutism.
• Findings support the significant role of MEAR and MOCB reflexes in the process of self-vocalization.
• Selective mutism may serve as a valuable human model for studying auditory efferent involvement in vocalization.