First Advisor

Marjorie Gordon-Brannan

Term of Graduation

Winter 1998

Date of Publication


Document Type


Degree Name

Master of Science (M.S.) in Speech Communication: Speech and Hearing Sciences


Speech Communication




Speech, Intelligibility of -- Testing, Children -- Language -- Testing



Physical Description

1 online resource (73 pages)


While speech-language pathologists routinely measure and report speech intelligibility when assessing young children with speech impairments, normative data have not been available for comparison purposes. When assessing children to determine if their communication abilities are at or below that of peers, one must first know what the normative standards are. Knowing the normal distribution for speech intelligibility at several ages would allow for more precise uses of the intelligibility information than is currently possible. Only a few available studies exist to allow tentative normative comparisons of speech intelligibility data (Vihman & Greenlee, 1987; Ware, 1996).

The goals of this pilot study were to collect normative data for normal 4-yearolds, +/-2 months, and to test procedural aspects of eliciting speech and determining speech intelligibility with listeners. Fifteen subjects were recruited in the greater Portland area. All were screened for normal hearing, expressive and receptive language, and phonological / articulation development. All subjects spoke English in the home and were reportedly free of motor, neurological, or developmental disorders. During the initial screening, all of the selected 15 subjects displayed normal behavior with no significant speech-language deviations.

The investigator recorded 15 speech samples on digital audiotape in a soundproof booth at the Portland State University Speech-Language and Hearing Clinic. The 15 samples were shortened to 100+ words and compiled on separate listening tapes. Three experienced graduate clinicians in speech-language pathology listened to the tapes with varied listening order. Listeners wrote full orthographic transcriptions, using slash marks for unintelligible words.

Once all samples were transcribed, the investigator compared them after determining a starting point, and took 100 continuous words from each subject to represent a sample. A word was counted as intelligible when at least two out of three listeners transcribed it the same. Speech intelligibility percentages were derived and compared to establish normative data for 4-year-olds, +/-2 months. One outlier percentage was removed from the data because the speech intelligibility percentage for that child was 28 percentage points lower than any other. The resulting sample size was 14. The mean intelligibility percentage was 94%, the median was 96%, and the standard deviation was 5.7.


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