Word-level prosodic measures and the differential diagnosis of apraxia of speech.
Katarina L Haley, Adam Jacks
PMID 30486684WHAT IT FOUND
Word syllable duration best separated apraxia of speech from aphasia and normal speech.
Stress-based measures failed because intrinsic vowel length distorted results. Use simple timing metrics for diagnosis, not complex stress ratios.
Key findings
01Word syllable duration (WSD) showed the least overlap between groups and was the most effective measure for distinguishing apraxia of speech from aphasia without apraxia and neurotypical controls.
02Measures of lexical stress (PVIdur and LSR) were significantly affected by the natural length of the vowels in the target words, making them unreliable for differential diagnosis.
03Speakers with aphasia without apraxia were indistinguishable from neurotypical controls on the word syllable duration measure, indicating high specificity for apraxia.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The sample size was small (35 participants), limiting the generalizability of the findings. The study did not measure vowel quality directly, so it is unclear how vowel errors influenced the duration results in the apraxia group. Reliability for the complex stress ratios was moderate, whereas reliability for word syllable duration was excellent. The findings are preliminary and require replication in larger samples before clinical cutoff scores can be established.
Declared interests
The authors report no conflicts of interest. The work was supported by the National Institutes of Health.
The easy way to misread this
Do not use lexical stress ratios (LSR or PVIdur) for differential diagnosis. These measures are confounded by the intrinsic duration of vowels, meaning a patient's score may reflect the specific words chosen rather than their actual ability to produce stress.