Need for Differential Diagnosis

By Pam Marshalla

Q: I have a six-year-old male client that has phonological and articulation problems. What should I target first in therapy?

Therapy always is based on the differential diagnosis.  It is impossible to answer that question without information about the client’s entire phonological and articulation repertoire. Selection of therapy targets will be very different depending upon many factors.

One makes decisions about therapy based upon a complete overview of what is going on.  If you read through this blog, you will see that I have answered many questions about how to stimulate this or that phoneme or phonological.  However I have never answered a question that stated, “My client has a problem with speech, what should I do?”  The question is far too broad and far too void of basic information that can help you make these kinds of decisions.

To make decisions about where to start in therapy one has to have information in at least the following areas. This is the core of the differential diagnosis for an expressive speech disorder, in my opinion ––


The client’s cognitive status, IQ, or cognitive age equivalency.

Receptive Language

The client’s receptive language level, vocabulary age, ability to follow directions, ability to answer questions.

Expressive Language Level

The client’s expressive language level. Non-verbal? Babbling? One-word level? Two-word level? Etc.


The status of the hearing mechanism.

Oral Structure

The status of oral structure.

Oral Function

What is the status of oral (jaw, lip, tongue, velum) control?


A complete inventory of phonological patterns.

Distinctive Features

An accounting of the distinctive features the client does and does not use.


A complete inventory of all the consonants that the client does and does not use.


A complete inventory of all the vowels the client does and does not use.


A complete inventory of the diphthongs she does and does not use.

Voice, Resonance, Prosody, and Fluency

A simple accounting of each area.


My analysis always includes an assessment of feeding skills as well, however I realize that this is not taught as a standard of practice.

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