ABSTRACT
This chapter describes speech sound disorders (SSD) of both known and unknown origins in line with the International Expert Panel definition, where SSD is “used as an umbrella term for the full range of speech sound difficulties of both known and presently unknown origin”. In childhood, it can be challenging to identify the prevalence of SSD in isolation, particularly when SSD and developmental language disorder frequently co-occur. There are large numbers of children with SSD on the caseloads of speech-language pathologists across the world. Genetic bases, hearing loss, craniofacial anomalies, motor impairments, autism spectrum disorder, and acquired brain injury can contribute to SSD of known origin. Motor impairments, autism spectrum disorder, and acquired brain injury may also be associated with SSD. SSD frequently co-occurs with other communication difficulties including language disorder, literacy difficulties, stuttering, and voice disorders. Assessment for SSD is typically completed by a speech-language pathologist.
