word measure

Expressive language impairment, speech
sound disorder and suspected childhood apraxia
of speech

TOCS+ Intelligibility measures were initially administered when this boy was 4 years 10 months old and re-administered at ages 5 years 10 months and 6 years 10 months. His intelligibility scores are shown in Figure 1.

Chart1Figure 1 - Percentage of Words Identified Correctly

His pattern of change in intelligibility scores over time is atypical:

.Typically, word intelligibility scores are on average about 10% lower than sentence intelligibility scores, due to the facilitating effects of context provided by sentence level utterances.  However, at the two younger ages, this boy’s word scores were higher than his sentence scores. 

.At age 6 years 10 months, his intelligibility scores were higher on the TOCS+ Sentence than Word measure, but these scores remained more than two standard deviations below the mean for our group of 6 year-old children with typical speech production.

.Our children with typical speech development have similar intelligibility scores from the TOCS+ Sentence measure and from a 100-word sample of spontaneous speech.  At age 6 years 10 months, this boy’s intelligibility scores are much lower for his spontaneous speech than for the TOCS+ Sentence measure.


Measures of speaking rate at age 6 years 10 months, shown in Table 1, revealed that he spoke much faster in his spontaneous speech than in the TOCS+ Sentence imitation task.   The almost 30% difference in his intelligibility scores between these two tasks may be explained by differences in speaking rate, mean length of utterance and grammar.  In the imitative sentence task, his speaking rate was considerably slower than in his spontaneous sample. Models may help to slow his speech rate, facilitate accurate articulation and thereby increase intelligibility. His mean length of utterance was calculated to be 6.7 words.  This is higher than the mean length of utterance for the TOCS+ Sentence measure, suggesting that the TOCS+ Sentence measure may not be representative of his spoken language use in his communication environments.

Finally there were five instances in the spontaneous sample where the copula (verb “to be”) was omitted.  Grammatical errors, in addition to his increased speech rate may make his speech more difficult to understand for unfamiliar listeners. An intelligibility deficit of this severity will likely have a negative impact on this boy’s spoken interactions in social and academic settings.  It was recommended that the child receive continued speech-language pathology services with a particular focus on decreasing his rate of speech, while maintaining clearly articulated sounds and increasing the accuracy of his use of grammatical morphemes and syntax.  


Intelligibility Score

Rate in words per minute

Mean Length of Utterance

Missing copula






Spontaneous Sample





Table 1 - Speaking Rate (Age: 6 yrs 10 mos)

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