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PCC

Percent Consonants Correct (PCC)

PCC indexes speech-sound accuracy by dividing correctly produced consonants by total consonant attempts in connected speech.

What PCC measures

Percent Consonants Correct, developed by Shriberg and Kwiatkowski in 1982, counts every consonant a child attempts in a connected-speech sample and classifies it as correct or in error (substitution, omission, or distortion). Dividing correct productions by total attempts gives a single percentage that indexes severity of articulation or phonological impairment on a continuum. Four severity bands — mild, mild-moderate, moderate-severe, severe — were published alongside the metric and have held up across decades of replication.

Formula

PCC = (correct consonants ÷ consonants attempted) × 100

Normative ranges and benchmarks

  • Age 3;0 — PCC ≈ 75%
  • Age 4;0 — PCC ≈ 85%
  • Age 5;0 — PCC ≈ 92%
  • Age 7;0 and up — PCC ≥ 98% in typical development
  • Severity bands: mild ≥ 85%, mild-moderate 65 – 85%, moderate-severe 50 – 65%, severe < 50%

Normative bands are central estimates drawn from the cited literature. Individual variation is wide — always cross-reference against the source paper and your assessment's own manual before quoting a cut-score in a report.

Clinical use

PCC is the standard indexing number for articulation and phonological disorder severity in research and the single most common "severity" line item in a speech report. It scales linearly with intelligibility — children with PCC under 65% are almost always rated as hard to understand by unfamiliar listeners. Its main constraint is that conversational-speech PCC is laborious to compute by hand because it requires every consonant in the sample to be classified. Most clinicians use an abbreviated PCC on a single-word articulation probe first, then sample-level PCC when needed for severity documentation or to track change over a block of therapy. Do not compute PCC from a 5-minute sample for a child whose speech is unintelligible — use a structured elicitation probe instead.

“A PCC of 62 is the number that moves a child from "monitor" to "direct therapy" on my caseload. It is one of the few LSA metrics whose cut-scores I actually quote to families verbatim, because the severity bands track their lived experience.”
A number families understand

Free tools that compute PCC

PCC Calculator

Free interactive Percent Consonants Correct (PCC) calculator for speech-language pathologists. Enter the consonants attempted and produced correctly from a 50- to 100-utterance connected-speech sample and get the PCC percent plus the Shriberg & Kwiatkowski (1982) severity band (mild, mild-moderate, moderate-severe, severe). Built for SLP intake, IEP eligibility, treatment-progress tracking, and graduate phonological-assessment training. Mobile-friendly, client-side, no sign-up.

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Articulation Screener

Free interactive articulation screener for speech-language pathologists. Tick errored sounds on a 30-word single-word probe covering every English consonant in at least one word position (initial, medial, final). The tool lists every errored sound, groups errors by position, and flags whether each sound is age-expected or past its McLeod & Crowe (2018) age of mastery — headline pass / at-cusp / refer decision in one keystroke. Modelled on the Goldman-Fristoe Test of Articulation 3 sounds-in-words structure and the Iowa-Nebraska norms (Smit et al. 1990). Mobile-friendly, client-side, no sign-up.

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Speech Sound Development Chart

Free interactive speech sound development chart for speech-language pathologists. Look up the age of acquisition for the 24 English consonants based on the McLeod & Crowe (2018) cross-linguistic systematic review. Filter by age band and word position (initial, medial, final), enter a child age and instantly see which sounds are age-expected versus still developing. Mobile-friendly, client-side, no sign-up.

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Related LSA metrics

TNW

Total Number of Words (TNW)

TNW is the raw word count in a language sample — the denominator behind almost every other LSA metric and a useful productivity index in its own right.

WPM

Words Per Minute (WPM / Speech Rate)

Words per minute divides total words by speaking time and indexes speech rate — useful for dysfluency, motor speech, and cognitive-linguistic populations.

PGU

Percent Grammatical Utterances (PGU)

PGU is the percentage of utterances in the sample that contain no morphosyntactic errors — the single best proxy for grammatical accuracy.

References

  1. Shriberg, L. D., & Kwiatkowski, J. (1982). Phonological disorders III: A procedure for assessing severity of involvement. JSHD, 47(3), 256–270.
  2. Shriberg, L. D., Austin, D., Lewis, B. A., McSweeny, J. L., & Wilson, D. L. (1997). The percentage of consonants correct (PCC) metric: Extensions and reliability data. JSLHR, 40(4), 708–722.
  3. Flipsen, P. Jr. (2006). Measuring the intelligibility of conversational speech in children. Clinical Linguistics & Phonetics, 20(4), 303–312.