For clinicians

SSD Differential Tool

For clinicians

SSD Differential Tool

Explore how speech sound disorders are classified, then compare profiles side by side. Click a profile in the tree to compare it with the profile it's most often confused with.

A comparison aid, not a diagnostic tool. The findings shown are typical, not required. Diagnosis rests on a comprehensive multilingual assessment, using appropriate methods for each language as far as feasible. Mixed presentations are common.

Classification tree

Click a profile (plum outline) to compare it. Click any other box to fold or unfold it.

Open to everyone

Childhood apraxia of speech vs inconsistent phonological disorder

How the tree is organised, and key sources

The first split follows ASHA's organic/functional framework; the functional branches follow Dodd's Model for Differential Diagnosis. ASHA classifies CAS as a motor speech disorder, so it sits on the organic side here, although Dodd lists it as one of five subgroups. The mapping between the two systems is approximate. "Not a distinguishing feature" means the feature isn't described as reliably separating this profile from others. It doesn't mean the feature is irrelevant or always typical.

Working through your own assessment findings?

With a free account you can compare any two profiles side by side, with notes on what helps separate them, and see every profile in one matrix.

The tree and the CAS and inconsistent phonological disorder comparison above stay open to everyone. The tool supports differential reasoning; it doesn't diagnose.