Selective Mutism

What Selective Mutism is

Selective mutism is classified in DSM-5-TR as an anxiety disorder in which a child consistently fails to speak in specific social situations where speaking is expected — typically school or unfamiliar community settings — despite speaking normally in other situations such as at home with family. The disorder usually onsets before age 5 and must persist for at least one month (excluding the first month of school) for diagnosis. It is not a language disorder per se — affected children have normal receptive and expressive language when comfortable — but it presents to SLPs through school-based referrals and sits in the SLP scope of practice as a co-assessment discipline with mental health.

Diagnostic criteria and defining features

• Consistent failure to speak in specific social situations where speaking is expected
• Normal speech in at least one other situation (typically home with family)
• Duration at least one month, not limited to the first month of school
• Failure to speak interferes with educational or social achievement
• Not better explained by language disorder, autism, or communication disorder

Criteria summarised from DSM-5-TR, ICD-11, and ASHA practice guidance. Always cross-reference against the diagnostic manual of record before using in a report.

How language sample analysis contributes

A traditional language sample in the clinic or classroom will often be impossible — the child will not produce any speech to sample. Clinicians should work with the family to obtain a home-recorded audio sample in a comfortable setting and run the standard metrics (MLU, NDW, TTR) on that recording to confirm that language ability is intact. The finding of age-appropriate expressive language at home with zero output at school is itself the diagnostic pattern. Once desensitisation therapy begins, repeated sampling across settings documents the generalisation of speech to new environments.

Related disorders