Parent rating of intelligibility: A discussion of the construct validity of the Intelligibility in Context Scale (ICS) and normative data of the Swedish version of the ICS.

BACKGROUND: Intelligibility can be defined as the speakers' ability to convey a message to the listener and it is considered the key functional measure of speech. The Intelligibility in Context Scale (ICS) is a parent rating scale used to assess intelligibility in children. AIMS: To describe normative and validation data on the ICS in Swedish and to investigate how these are related to age, gender and multilingualism. METHODS & PROCEDURES: Two studies were included. Study 1 included ICS forms from 319 Swedish-speaking children (3:2-9:2 years:months). Study 2 included video recordings and ICS forms from 14 children with speech sound disorder (SSD) and two with typical speech. The video recordings were transcribed in the validation process, resulting in intelligibility reference scores to which ICS scores were correlated. OUTCOMES & RESULTS: Study 1: The mean value of the ICS for the 319 children was 4.73. There were no differences in ICS score related to age or gender. The children in the multilingual group were significantly older than the monolingual group and had significantly lower ICS scores than the group of monolinguals. Study 2: There was a moderate correlation between the ICS score and the transcription-based intelligibility score, with the two children with typical speech excluded; however, this correlation was not significant. CONCLUSIONS & IMPLICATIONS: We contribute mean scores and percentiles on the ICS for Swedish-speaking children. The finding that the ICS does not provide valid measures of intelligibility for the included children with SSD suggests that the instrument measures a different construct. WHAT THIS PAPER ADDS: What is already known on the subject The ICS has been translated to numerous languages and validated against articulation measures in several previous studies. The validity of the Swedish version has been investigated against intelligibility based on transcription of single words. What this paper adds to existing knowledge The study provides normative values of the Swedish version of the ICS for children aged 3-9 years. This is the first study to use a gold standard measure of intelligibility in continuous speech to validate the ICS. The results show a somewhat dubious validity regarding ICS for the group of children with SSD included in the study. What are the potential or actual clinical implications of this work? The ICS's suitability as a measure of intelligibility is questionable; however, it might be of use for speech and language pathologists to give an overview of the parents' view of their child's ability to communicate, in order to make a decision on possible further assessment and intervention. The normative values of the Swedish version of the ICS could be of use in this decision process.

Measuring intelligibility in spontaneous speech using syllables perceived as understood.

PURPOSE: Intelligibility, the ability to convey a message by speech, is one of the most important variables in speech-language pathology. The assessment of intelligibility is a challenge especially when it comes to spontaneous speech. The aim of the study was to investigate validity and reliability of a method for assessment of intelligibility, syllables perceived as understood (SPU); a method that is more time-efficient than previous methods based on transcription, as it does not require a master transcript for reference. METHOD: A group of 20 adult listeners transcribed stimuli consisting of spontaneous speech from 16 children (14 with speech sound disorder and two with typical speech and language development, age 4:4 to 8:1, M = 6:0). Intelligibility was calculated based on these orthographic transcripts, as a) proportion of syllables perceived as understood (SPU) and b) proportion of syllables correctly understood (SCU), with reference to a master transcript. Validity was checked through investigation of the correlation and difference between these two measures. Reliability was analysed with inter-listener reliability by intra-class correlation. RESULTS: The correlation between SPU and SCU (the gold standard intelligibility score) was strong and statistically significant, with SPU being consistently higher than SCU. Inter-listener reliability for single measures of intra-class correlation of the assessment by syllables perceived as understood was moderate to low, whereas the inter-listener reliability for average measures of intra-class correlation was high. CONCLUSIONS: The method based on SPU might be used for assessment of intelligibility if the median from several listeners is used or when comparing results from the same listener over time. The SPU method might therefore be a valuable tool in a clinical and research context as a more valid option than rating scales and a more time-efficient method than the gold standard SCU method. However, it should be noted that the reliability of the SPU is not as high as for the SCU.

Intelligibility of Children With Speech Sound Disorders Evaluated by Listeners With Swedish as a Second Language.

Purpose This study aimed to investigate the intelligibility of children's atypical speech in relation to listeners' language background. Method Forty-eight participants listened to and transcribed isolated words repeated by children with speech sound disorders. Participants were divided into, on the one hand, a multilingual group (n = 29) that was further divided into subgroups based on age of acquisition (early, 0-3 years; intermediate, 4-12 years; and late, > 12 years) and, on the other hand, a monolingual comparison group (n = 19). Results The monolingual listeners obtained higher intelligibility scores than the multilingual listeners; this difference was statistically significant. Participants who acquired Swedish at an older age (> 4 years) were found to have lower scores than other listeners. The later the age of acquisition, the less of the atypical speech was decoded correctly. A further analysis of the transcriptions also revealed a higher level of nonwords among the incorrect transcriptions of the multilinguals than that of the monolinguals who used more real words, whereas both groups were equally prone to using blanks when they did not perceive a word. Conclusions This indicates a higher risk of communicative problems between late acquirers of Swedish and children with speech sound disorders. Clinical implications, such as involving communication partners in the intervention process, are discussed as well as possible linguistic explanations to the findings. This study could be seen as a starting point in the field of research regarding the relations between the language background of the listener and the ability to perceive atypical speech.

An Investigation of the Clinical Use of a Single-Word Procedure to Assess Intelligibility (Swedish Test of Intelligibility for Children) and an Evaluation of the Validity and Reliability of the Intelligibility in Context Scale.

Purpose Intelligibility is a core concept of speech-language pathology, central both to the assessment of speech disorders and to intervention in such disorders. One purpose of this study was to investigate the reliability and usability of a single-word assessment procedure, the Swedish Test of Intelligibility for Children (STI-CH), in a clinical setting. Another purpose was to investigate the validity and reliability of an assessment method designed to assess functional intelligibility: the Intelligibility in Context Scale (ICS). Method Thirty children aged 4;1-10;1 years;months were recruited from speech-language pathology clinics in Western Sweden. Each child's treating speech-language pathologist served as listener in the STI-CH assessment while the ICS was completed by each child's parents. External listeners (2 last-year speech-language pathology students) were used to assess the validity of the speech-language pathology. Results The mean duration of the test procedure for the STI-CH was about 19 min, and 57% of the test sessions were reported as difficult. There was a weak but statistically significant correlation between the results from the STI-CH and the ICS ( r = .40, p < .05), and both methods showed high reliability in terms of interlistener reliability (intraclass correlation exceeding .97) and internal consistency, respectively. Conclusions The STI-CH had high reliability and was time efficient but had some procedural problems. The ICS had moderate validity but high reliability. The STI-CH is promising for clinical use but needs to be developed further. The validity of the ICS can be discussed and needs to be further investigated.

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.

Swedish Test of Intelligibility for Children (STI-CH)--validity and reliability of a computer-mediated single word intelligibility test for children.

The aim of this study was twofold: first, to describe a new Swedish intelligibility test (Swedish Test of Intelligibility for Children, STI-CH) and second to evaluate its validity and reliability. STI-CH is based on the repetition of single words. Ten children with a speech-sound disorder (4:6-8:3 years of age, mean = 6.0 years) and 10 children with typical speech and language development (4:8-7:4 years of age, mean = 5.9 years) were included. Twenty speech-language pathology students served as listeners. Intra-judge reliability was high (r > 0.92), as was the intra-class correlation of inter-judge reliability (0.97). In terms of validity, there was a significant difference in STI-CH scores between the two groups, and the scores correlated statistically significantly with the Percentage of Consonants Correct (r = 0.94) and with intelligibility in spontaneous speech (r = 0.85). To sum up, the results indicate that STI-CH could be an option for the assessment of intelligibility in Swedish-speaking children, and that the principles used in the development of the test could be of use in the design of intelligibility tests in languages other than Swedish.

Assessment of intelligibility using children's spontaneous speech: methodological aspects.

BACKGROUND: Intelligibility is a speaker's ability to convey a message to a listener. Including an assessment of intelligibility is essential in both research and clinical work relating to individuals with communication disorders due to speech impairment. Assessment of the intelligibility of spontaneous speech can be used as an overall indicator of the severity of a speech disorder. There is a lack of methods for measuring intelligibility on the basis of spontaneous speech. AIMS: To investigate the validity and reliability of a method where listeners transcribe understandable words and an intelligibility score is calculated on the basis of the percentage of syllables perceived as understood. METHODS & PROCEDURES: Spontaneous speech from ten children with speech-sound disorders (mean age = 6.0 years) and ten children with typical speech and language development (mean age = 5.9 years) was recorded and presented to 20 listeners. Results were compared between the two groups and correlation with percentage of consonants correct (PCC) was examined. OUTCOMES & RESULTS: The intelligibility scores obtained correlated with PCC in single words and differed significantly between the two groups, indicating high validity. Inter-judge reliability, analysed using intra-class correlation (ICC), was excellent in terms of the average measure for several listeners. CONCLUSIONS & IMPLICATIONS: The results suggest that this method can be recommended for assessing intelligibility, especially if the mean across several listeners is used. It could also be used in clinical settings when evaluating intelligibility over time, provided that the same listener makes the assessments.