Clinical experience and categorical perception of children's speech

Listening like a speech-training app: Expert and non-expert listeners' goodness ratings of children's speech

Speech training apps are being developed that provide automatic feedback concerning children's production of known target words, as a score on a 1-5 scale. However, this 'goodness' scale is still poorly understood. We investigated listeners' ratings of 'how many stars the app should provide as feedback' on children's utterances, and whether listener agreement is affected by clinical experience and/or access to anchor stimuli. In addition, we explored the association between goodness ratings and clinical measures of speech accuracy; the Percentage of Consonants Correct (PCC) and the Percentage of Phonemes Correct (PPC). Twenty speech-language pathologists and 20 non-expert listeners participated; half of the listeners in each group had access to anchor stimuli. The listeners rated 120 words, collected from children with and without speech sound disorder. Concerning reliability, intra-rater agreement was generally high, whereas inter-rater agreement was moderate. Access to anchor stimuli was associated with higher agreement, but only for non-expert listeners. Concerning the association between goodness ratings and the PCC/PPC, correlations were moderate for both listener groups, under both conditions. The results indicate that the task of rating goodness is difficult, regardless of clinical experience, and that access to anchor stimuli is insufficient for achieving reliable ratings. This raises concerns regarding the 1-5 rating scale as the means of feedback in speech training apps. More specific listener instructions, particularly regarding the intended context for the app, are suggested in collection of human ratings underlying the development of speech training apps. Until then, alternative means of feedback should be preferred.

Auditory-perceptual evaluation with visual analogue scale: feasibility and preliminary evidence of ultrasound visual feedback treatment of Finnish [r]

Accumulating evidence suggests that ultrasound visual feedback increases the treatment efficacy for persistent speech sound errors. However, the available evidence is mostly from English. This is a feasibility study of ultrasound visual feedback for treating distortion of Finnish [r]. We developed a web-based application for auditory-perceptual judgement. We investigated the impact of listener's experience on perceptual judgement and the intra-rater reliability of listeners. Four boys (10-11 years) with distortion of [r], otherwise typical development, partook in eight ultrasound treatment sessions. In total, 117 [r] samples collected at pre- and post-intervention were judged with visual analogue scale (VAS) by two listener groups: five speech and language therapists (SLTs) and six SLT students. We constructed a linear mixed-effects model with fixed effects for time and listener group and several random effects. Our findings indicate that measurement time had a significant main effect on judgement results, χ² = 78.82, p < 0.001. Effect of listener group was non-significant, but a significant main effect of interaction of group × time, χ² = 6.33, p < 0.012 was observed. We further explored the effect of group with nested models, and results revealed a non-significant effect of group. The average intra-rater correlation of the 11 listeners was 0.83 for the pre-intervention samples and 0.92 for post-intervention showing a good or excellent degree of agreement. Finnish [r] sound can be evaluated with VAS and ultrasound visual feedback is a feasible and promising method in treatment for distortion of [r], and its efficacy should be further assessed.

Covert contrasts and categorical perception: a comparison of two measurement tools

This study considers adults' perception of subtle differences in the error productions of /r/ and /l/ in young children. Given that these two phonemes share a common substitution [w], the potential covert contrast between these three sounds was investigated. The utility of two perceptual rating scales was compared: a linear visual analogue scale (VAS) and a triangular scale that considered the possibility of covert contrast among /r,l,w/. Adult listeners rated speech productions from children with cochlear implants (CIs) and speech age-matched children with normal hearing (NH) as they produced VCV or CV productions with /r,l,w/ in syllable-initial position. Mahalanobis distances of the listener ratings for each stimulus on each rating scale were calculated for analysis. Ultimately, there was no difference between the ratings of the two speaker populations. However, there was a significant difference in the amount of variability captured with each scale. The triangular scale reliably captured more variability in the productions than the linear VAS. The significant effect of scale type on the spread of listeners' responses provides support for the claim that the type of rating system used can capture different aspects of a listener's perceptions, thereby suggesting that the type of rating system used in a study may significantly influence that study's findings.

The myth of categorical perception

Categorical perception (CP) is likely the single finding from speech perception with the biggest impact on cognitive science. However, within speech perception, it is widely known to be an artifact of task demands. CP is empirically defined as a relationship between phoneme identification and discrimination. As discrimination tasks do not appear to require categorization, this was thought to support the claim that listeners perceive speech solely in terms of linguistic categories. However, 50 years of work using discrimination tasks, priming, the visual world paradigm, and event related potentials has rejected the strongest forms of CP and provided little strong evidence for any form of it. This paper reviews the origins and impact of this scientific meme and the work challenging it. It discusses work showing that the encoding of auditory input is largely continuous, not categorical, and describes the modern theoretical synthesis in which listeners preserve fine-grained detail to enable more flexible processing. This synthesis is fundamentally inconsistent with CP. This leads to a different understanding of how to use and interpret the most basic paradigms in speech perception-phoneme identification along a continuum-and has implications for understanding language and hearing disorders, development, and multilingualism.

Don't force it! Gradient speech categorization calls for continuous categorization tasks

Research on speech categorization and phoneme recognition has relied heavily on tasks in which participants listen to stimuli from a speech continuum and are asked to either classify each stimulus (identification) or discriminate between them (discrimination). Such tasks rest on assumptions about how perception maps onto discrete responses that have not been thoroughly investigated. Here, we identify critical challenges in the link between these tasks and theories of speech categorization. In particular, we show that patterns that have traditionally been linked to categorical perception could arise despite continuous underlying perception and that patterns that run counter to categorical perception could arise despite underlying categorical perception. We describe an alternative measure of speech perception using a visual analog scale that better differentiates between processes at play in speech categorization, and we review some recent findings that show how this task can be used to better inform our theories.

'I think that's what I heard? I'm not sure': Speech and language therapists' views of, and practices in, phonetic transcription

BACKGROUND

Phonetic transcription is recognized in regulatory standards as an essential skill for Speech and Language Therapists (SLTs) in the assessment, diagnosis and management of clients with speech difficulties. Previous research has identified that approaches to phonetic transcription vary, and that SLTs often lack confidence in transcribing. However, SLTs' views and working practices have not been investigated in detail, particularly in terms of whole service approaches and following the recent increase in telehealth.

AIMS

To investigate SLTs' views about phonetic transcription, their working practices at both individual and service levels, and the factors that influence these.

METHODS & PROCEDURES

A total of 19 SLTs from the UK were recruited to online focus groups via social media and local networks. Participants discussed their views of, and practices in, phonetic transcription. Themes were identified using reflexive thematic analysis.

OUTCOMES & RESULTS

Three broad themes were generated division and unity; one small part of a big job; and fit for purpose. SLTs were uniformly proud of their ability to phonetically transcribe and viewed this as a unique skill, but clear differences existed between different groups of SLTs in their views and practices. Investing in phonetic transcription was not always a priority for SLTs or services, and although many felt under-confident in their skills they considered these to be adequate for the populations they usually encounter. SLTs make an early judgement about possible therapy targets, which influences the level of detail used in their phonetic transcription. Practical barriers are often not addressed at service level, and assessment via telehealth poses some specific challenges.

CONCLUSIONS & IMPLICATIONS

SLTs and services would benefit from increased investment in phonetic transcription in terms of time, opportunities for continuing professional development (CPD) and initiatives such as electronic patient records (EPRs) which support the use of phonetic symbols. Identifying target sounds at an early stage raises questions about the implications of disregarding other features of speech, and the selection of appropriate intervention approaches. Further research is needed to analyse actual rather than reported practices, and to consider the relationship between phonetic transcription and intervention approaches. Future studies could also identify precise CPD requirements and evaluate the effectiveness of CPD.

WHAT THIS PAPER ADDS

What is already known on the subject Previous research has demonstrated that SLTs often lack confidence in phonetic transcription and that practices are varied, with relatively little use of narrow transcription. SLTs are interested in opportunities to maintain and develop transcription skills but do not often undertake CPD for transcription. What this paper adds to existing knowledge By using focus groups as a forum for discussions, this study provides a rich and detailed insight into SLTs' views about clinical transcription and their working practices, with previously unreported details about the reasons for these practices in a clinical context and at a service-wide level. What are the potential or actual clinical implications of this work? Transcription is often de-prioritized in non-specialist contexts, with practical barriers and a lack of clear and consistent protocols at a whole-service level. There is an opportunity for service managers to address the systemic difficulties in using transcription effectively by raising the profile and value of transcription amongst clinicians, and promoting CPD opportunities, using the findings of this study as a rationale for funding this. Together, these recommendations have the potential to improve client outcomes through more accurate assessment and diagnosis, and hence more appropriate intervention.

Baseline Stimulability Predicts Patterns of Response to Traditional and Ultrasound Biofeedback Treatment for Residual Speech Sound Disorder

PURPOSE

This study aimed to identify predictors of response to treatment for residual speech sound disorder (RSSD) affecting English rhotics. Progress was tracked during an initial phase of traditional motor-based treatment and a longer phase of treatment incorporating ultrasound biofeedback. Based on previous literature, we focused on baseline stimulability and sensory acuity as predictors of interest.

METHOD

Thirty-three individuals aged 9-15 years with residual distortions of /ɹ/ received a course of individual intervention comprising 1 week of intensive traditional treatment and 9 weeks of ultrasound biofeedback treatment. Stimulability for /ɹ/ was probed prior to treatment, after the traditional treatment phase, and after the end of all treatment. Accuracy of /ɹ/ production in each probe was assessed with an acoustic measure: normalized third formant (F3)-second formant (F2) distance. Model-based clustering analysis was applied to these acoustic measures to identify different average trajectories of progress over the course of treatment. The resulting clusters were compared with respect to acuity in auditory and somatosensory domains.

RESULTS

All but four individuals were judged to exhibit a clinically significant response to the combined course of treatment. Two major clusters were identified. The "low stimulability" cluster was characterized by very low accuracy at baseline, minimal response to traditional treatment, and strong response to ultrasound biofeedback. The "high stimulability" group was more accurate at baseline and made significant gains in both traditional and ultrasound biofeedback phases of treatment. The clusters did not differ with respect to sensory acuity.

CONCLUSIONS

This research accords with clinical intuition in finding that individuals who are more stimulable at baseline are more likely to respond to traditional intervention, whereas less stimulable individuals may derive greater relative benefit from biofeedback.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20422236.