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A few comments:

First, PCC (Percentage Consonants Correct) is a measure of speech sound
accuracy. It is NOT a measure of intelligibility which reflects how much of
the intended meaning can be recovered by the listener (i.e., how much was
understood regardless of how accurately it was produced).

Second, in their classic 1982 study, Shriberg and Kwiatkowski showed that if
you calculate PCC from a narrow transcription of a conversational speech
sample, the value you obtain is nicely correlated with clinician ratings of
severity (mild, moderate, etc.).

Third, in a study published in 2005, my co-authors and I looked at a number
of other measures to see if any of them were any better at capturing the
severity ratings of experienced clinicians than PCC. Although some were
slightly better, all seemed to require more complex calculations - PCC still
appears to do as good a job as any.

Fourth, Garret and Moran in 1992 demonstrated that phonological deviancy
score (from Hodson's test) may work similarly to PCC in capturing what
clinicians come up with for severity ratings.

Fifth, there is no gold standard for assigning severity to speech sound
disorders. That's why clinician opinion tends to be used as the point of
comparison in studies in this area.

Sixth, there have been many suggested ways of determining severity beyond
the measures discussed in these papers, but all are essentially somewhat
arbitrary and/or based solely on expert opinion. fyi - ASHA has actually
developed a severity scale for speech sound disorders a few years ago, but
it's buried in one of their "guidelines" documents that I can't seem to
locate on their website at the moment. When I get back to my office
tomorrow I'll see if I can track it down. But alas, it too was developed by
an expert panel and is largely "opinion".

Lastly, a question - what exactly do you mean when you say "phonological
difficulties" and how do you differentiate it from "articulation

Peter Flipsen Jr


Flipsen, Jr., P.; Hammer, JB and Yost, KM (2005). *Measuring Severity of
Involvement in Speech Delay: Segmental and Whole-Word Measures *Am J Speech
Lang Pathol, 14: 298 - 312.

Garret, KK and Moran, MJ (1992) *A comparison of phonological severity
measures.* Lang Hear Speech Serv in Schools, 23, 48-51.

Shriberg, LD and Kwiatkowski, J (1982). *Phonological Disorders III: A
Procedure for Assessing Severity of Involvement*
J Speech Hear Disord, 47: 256 - 270.

On Tue, Jul 27, 2010 at 8:00 PM, rach_ev2003 <> wrote:

> Hi Group,
> In looking into different types of therapy for the above, and noting that
> some are indicated for varying severeity levels of the same, it made me
> question how do I go about rating a phonological difficulty in terms of
> mild/moderate/severe?
> I have read that in terms of articulation, it is common to use
> intelligibility measured via PCC to rate severity (if required) but was
> wondering if the process is the same for rating phonological difficulties?
> I await your valued feedback on the same.
> Kind regards

[Non-text portions of this message have been removed]

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