Dataset Information

A Statistical Method for the Analysis of Speech Intelligibility Tests.

ABSTRACT: Speech intelligibility tests are conducted on hearing-impaired people for the purpose of evaluating the performance of a hearing device under varying listening conditions and device settings or algorithms. The speech reception threshold (SRT) is typically defined as the signal-to-noise ratio (SNR) at which a subject scores 50% correct on a speech intelligibility test. An SRT is conventionally measured with an adaptive procedure, in which the SNR of successive sentences is adjusted based on the subject's scores on previous sentences. The SRT can be estimated as the mean of a subset of the SNR levels, or by fitting a psychometric function. A set of SRT results is typically analyzed with a repeated measures analysis of variance. We propose an alternative approach for analysis, a zero-and-one inflated beta regression model, in which an observation is a single sentence score rather than an SRT. A parametrization of the model is defined that allows efficient maximum likelihood estimation of the parameters. Fitted values from this model, when plotted against SNR, are analogous to a mean psychometric function in the traditional approach. Confidence intervals for the fitted value curves are obtained by parametric bootstrap. The proposed approach was applied retrospectively to data from two studies that assessed the speech perception of cochlear implant recipients using different sound processing algorithms under different listening conditions. The proposed approach yielded mean SRTs for each condition that were consistent with the traditional approach, but were more informative. It provided the mean psychometric curve of each condition, revealing differences in slope, i.e. differential performance at different parts of the SNR spectrum. Another advantage of the new method of analysis is that results are stated in terms of differences in percent correct scores, which is more interpretable than results from the traditional analysis.

SUBMITTER: Hu W

PROVIDER: S-EPMC4493151 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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A Statistical Method for the Analysis of Speech Intelligibility Tests.

Hu Wenli W Swanson Brett A BA Heller Gillian Z GZ

PloS one 20150706 7

Speech intelligibility tests are conducted on hearing-impaired people for the purpose of evaluating the performance of a hearing device under varying listening conditions and device settings or algorithms. The speech reception threshold (SRT) is typically defined as the signal-to-noise ratio (SNR) at which a subject scores 50% correct on a speech intelligibility test. An SRT is conventionally measured with an adaptive procedure, in which the SNR of successive sentences is adjusted based on the s ...[more]

PMID: 26147290

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Project description:Listeners vary in their ability to understand speech in noisy environments. Hearing sensitivity, as measured by pure-tone audiometry, can only partly explain these results, and cognition has emerged as another key concept. Although cognition relates to speech perception, the exact nature of the relationship remains to be fully understood. This study investigates how different aspects of cognition, particularly working memory and attention, relate to speech intelligibility for various tests. Perceptual accuracy of speech perception represents just one aspect of functioning in a listening environment. Activity and participation limits imposed by hearing loss, in addition to the demands of a listening environment, are also important and may be better captured by self-report questionnaires. Understanding how speech perception relates to self-reported aspects of listening forms the second focus of the study. Forty-four listeners aged between 50 and 74 years with mild sensorineural hearing loss were tested on speech perception tests differing in complexity from low (phoneme discrimination in quiet), to medium (digit triplet perception in speech-shaped noise) to high (sentence perception in modulated noise); cognitive tests of attention, memory, and non-verbal intelligence quotient; and self-report questionnaires of general health-related and hearing-specific quality of life. Hearing sensitivity and cognition related to intelligibility differently depending on the speech test: neither was important for phoneme discrimination, hearing sensitivity alone was important for digit triplet perception, and hearing and cognition together played a role in sentence perception. Self-reported aspects of auditory functioning were correlated with speech intelligibility to different degrees, with digit triplets in noise showing the richest pattern. The results suggest that intelligibility tests can vary in their auditory and cognitive demands and their sensitivity to the challenges that auditory environments pose on functioning.

Project description:The goal of this research was to assess the support for motor speech disorders as explanatory constructs to guide research and treatment of reduced intelligibility in persons with Down syndrome (DS). Participants were the 45 adolescents with DS in the prior paper who were classified into five mutually-exclusive motor speech classifications using the Speech Disorders Classification System. An ordinal index classified participants' percentage of intelligible words in conversation as High (≥ 85%), Moderate (80% - 84.9%), or Low (< 80%). Statistical analyses tested for significant differences in intelligibility status associated with demographic, intelligence, and language variables, and intelligibility status associated with motor speech classifications and speech, prosody, and voice variables. For the 10 participants who met criteria for concurrent Childhood Dysarthria and Childhood Apraxia of Speech at assessment, 80% had reduced (Moderate or Low) intelligibility and 20% had High intelligibility (significant effect size: 0.644). Proportionally more of the 32 participants who met criteria for either dysarthria or apraxia had reduced intelligibility (significant effect size: 0.318). Low intelligibility was significantly associated with across-the-board reductions in phonemic and phonetic accuracy and with inappropriate prosody and voice. Findings are interpreted as support for motor speech disorders in adolescents with DS as explanatory constructs for their reduced intelligibility. Pending cross-validation of findings in diverse samples of persons with DS, studies are needed to assess the efficacy of motor speech classification status to guide selection of treatment methods and intelligibility targets. Abbreviations: CAS: Childhood Apraxia of Speech; CD: Childhood Dysarthria; DS: Down syndrome; II: Intelligibility Index; No MSD: No Motor Speech Disorder; OII: Ordinal Intelligibility Index; PSD: Persistent Speech Delay; SDCS: Speech Disorders Classification System; SMD: Speech Motor Delay.

Project description:PurposeThe purpose of this study was to investigate the association between perceived single-word speech severity and intelligibility in children with childhood apraxia of speech (CAS), with and without comorbid language impairment (LI), and to investigate the contribution of different CAS signs to perceived single-word speech severity and single-word intelligibility.MethodThirty children with CAS, 18 with comorbid LI, completed the Goldman-Fristoe Test of Articulation-Second Edition (GFTA-2). Trained judges coded children's responses for signs of CAS and percent phonemes correct. Nine listeners, blind to diagnoses, rated speech severity using a visual analog scale. Intelligibility was assessed by comparing listeners' orthographic transcriptions of children's responses to target responses.ResultsMeasures of speech severity (GFTA-2 standard score, number of unique CAS signs, total CAS signs, and mean severity rating) were significantly correlated with measures of intelligibility (GFTA-2 raw score, percent phonemes correct, and mean intelligibility score). Speech severity and intelligibility did not differ significantly between children with and without LI. Only consonant errors contributed significant variability to speech severity. Consonant errors and stress errors contributed significant variability to intelligibility.ConclusionsFindings suggest that visual analog scale ratings are a valid and convenient measure of single-word speech severity and that GFTA-2 raw score is an equally convenient measure of single-word intelligibility. The result that consonant errors were by far the major contributor to single-word speech severity and intelligibility in children with CAS, with stress errors also making a small contribution to intelligibility, suggests that consonant accuracy and appropriate lexical stress should be prime therapeutic targets for these children in the context of treatment addressing motor planning/programming, self-monitoring, and self-correcting.Supplemental materialhttps://doi.org/10.23641/asha.19119350.

Dataset Information

A Statistical Method for the Analysis of Speech Intelligibility Tests.

Publications

A Statistical Method for the Analysis of Speech Intelligibility Tests.

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