Effect of the number of presentations on listener transcriptions and reliability in the assessment of speech intelligibility in children.

Background: The assessment of intelligibility is an essential part of establishing the severity of a speech disorder. The intelligibility of a speaker is affected by a number of different variables relating, inter alia, to the speech material, the listener and the listener task.

Aims: To explore the impact of the number of presentations of the utterances on assessments of intelligibility based on orthographic transcription of spontaneous speech, specifically the impact on intelligibility scores, reliability and intra-listener variability.

Methods & Procedures: Speech from 12 children (aged 4:6-8:3 years; mean = 5:10 years) with percentage consonants correct (PCC) scores ranging from 49 to 81 was listened to by 18 students on the speech-language pathology (SLP) programme and by two recent graduates from that programme. Three conditions were examined during the transcription phase: (1) listening to each utterance once; (2) listening to each utterance a second time; and (3) listening to all utterances from a given child a third time after having heard all of its utterances twice.

Outcomes & Results: Statistically significant differences between intelligibility scores were found across the three conditions, i.e. the intelligibility score increased with the number of presentations while inter-judge reliability was unchanged. The results differed markedly across listeners, but each individual listener's results were very consistent across conditions.

Conclusions & Implications: Information about the number of times an utterance is presented to the listener is important and should therefore always be included in reports of research involving intelligibility assessment. There is a need for further research and discussion on listener abilities and strategies.