Intelligibility Of Speakers Research Articles

Progress Toward Estimating the Minimal Clinically Important Difference of Intelligibility: A Crowdsourced Perceptual Experiment.

The purpose of the current study was to estimate the minimal clinically important difference (MCID) of sentence intelligibility in control speakers and in speakers with dysarthria due to multiple sclerosis (MS) and Parkinson's disease (PD). Sixteen control speakers, 16 speakers with MS, and 16 speakers with PD were audio-recorded reading aloud sentences in habitual, clear, fast, loud, and slow speaking conditions. Two hundred forty nonexpert crowdsourced listeners heard paired conditions of the same sentence content from a speaker and indicated if one condition was more understandable than another. Listeners then used the Global Ratings of Change (GROC) Scale to indicate how much more understandable that condition was than the other. Listener ratings were compared with objective intelligibility scores obtained previously via orthographic transcriptions from nonexpert listeners. Receiver operating characteristic (ROC) curves and average magnitude of intelligibility difference per level of the GROC Scale were evaluated to determine the sensitivity, specificity, and accuracy of potential cutoff scores in intelligibility for establishing thresholds of important change. MCIDs derived from the ROC curves were invalid. However, the average magnitude of intelligibility difference derived valid and useful thresholds. The MCID of intelligibility was determined to be about 7% for a small amount of difference and about 15% for a large amount of difference. This work demonstrates the feasibility of the novel experimental paradigm for collecting crowdsourced perceptual data to estimate MCIDs. Results provide empirical evidence that clinical tools for the perception of intelligibility by nonexpert listeners could consist of three categories, which emerged from the data ("no difference," "a little bit of difference," "a lot of difference"). The current work is a critical step toward development of a universal language with which to evaluate changes in intelligibility as a result of neurological injury, disease progression, and speech-language therapy.

Impact of perceptual-learning strategies and background noise on disordered speech intelligibility

Objective: There is a plethora of research showing reduced speech intelligibility for a variety of voice disorders (i.e., dysphonia, alaryngeal). Therapeutic approaches to improve intelligibility typically involve targeting the speaker (e.g., clear speech, reduced rate) with minimal attention to the listener. Therefore, there were three purposes of this study: 1) to determine the impact of background noise on the speech intelligibility of disordered speakers; 2) to determine the impact of providing listeners with perceptual-learning strategies on the speech intelligibility of speakers with a voice disorder; and 3) to determine if subjective ratings of voice quality can predict speech intelligibility. Methods: Sentences were recorded from 12 speakers (2 typical, 3 alaryngeal, 7 dysphonic). Sentences were divided into one of three groups of signal-to-noise ratios (SNR: quiet, +5 dB SNR, and 0 dB SNR) and individually presented to 129 healthy listeners divided into one of three groups (i.e., control, acknowledgment of disorder, cognitive-perceptual strategies). Orthographic transcription was used to assess speech intelligibility. In addition, three expert listeners provided subjective voice quality ratings of all speakers. Results: Listeners had significantly more intelligibility errors with increased background noise (p <.001) and providing strategies to listeners did not result in a statistical improvement level F(6, 486) = 1.53, p = .17, η2p = 0.02. Regression analysis showed that the subjective voice quality overall severity was able to predict speech intelligibility in the noisy condition (0 dB SNR), accounting for 37% of the variance, R2 = .365, F(1,10) = 5.759, p = .037. Conclusion: Results suggest that increased background noise has a deleterious effect on the speech intelligibility of those with a voice disorder but that providing listeners with strategies in hopes of improving speaker intelligibility was not successful. Results did provide support, however, for the use of subjective voice quality ratings as a potential index of speech intelligibility.

Dialect identification, intelligibility ratings, and acceptability ratings of dysarthric speech in two American English dialects

ABSTRACT The current study explored the intelligibility and acceptability ratings of dysarthric speakers with African American English (AAE) and General American English (GAE) dialects by listeners who identify as GAE or AAE speakers, as well as listener ability to identify dialect in dysarthric speech. Eighty-six listeners rated the intelligibility and acceptability of sentences extracted from a passage read by speakers with dysarthria. Samples were used from the Atlanta Motor Speech Disorders Corpus and ratings were collected via self-report. The listeners identified speaker dialect in a forced-choice format. Listeners self-reported their dialect and exposure to AAE. AAE dialect was accurately identified in 63.43% of the the opportunities; GAE dialect was accurately identified in 70.35% of the opportunities. Listeners identifying as AAE speakers rated GAE speech as more acceptable, whereas, listeners identifying as GAE speakers rated AAE speech as more acceptable. Neither group of listeners demonstrated a difference in intelligibility ratings. Exposure to AAE had no effect on intelligibility or acceptability ratings. Listeners can identify dialect (AAE and GAE) with a better than chance degree of accuracy. One’s dialect may have an effect on intelligibility and acceptability ratings. Exposure to a dialect did not affect listener ratings of intelligibility or acceptability.

Vowel articulation and intelligibility of speech in Spanish speakers with Parkinson's disease treated with deep brain stimulation of the subthalamic nucleus

Parkinson's disease (PD) can affect the intelligibility of speech. Although studies of vowel production are useful for measuring this impairment, they do not exist in Spanish speakers with the disease who have been treated with subthalamic nucleus deep brain stimulation (STN-DBS). STN-DBS is an effective treatment for the classic signs of PD, but with varied effects on speech. Data from two individuals with PD treated with STN-DBS were studied: one (P1) had impairment and the other (P2) had stable speech intelligibility after STN-DBS implantation. The triangular vowel space area (tVSA) and the vowel articulation index (VAI) were measured and compared before the implantation surgery, and at three, six and nine months after surgery. These measurements were compared with measurements of speech intelligibility (percentage of words correctly identified and degree of intelligibility). Both participants presented variations in measurements of vowel articulation after surgery. In P1, the reduction in the tVSA, but not the post-surgical change in the VAI, was consistent with reduced speech intelligibility. However, in P2, both measurements (tVSA and VAI) reflected stable speech intelligibility after surgery. Reduced speech intelligibility in Spanish speakers with PD after STN-DBS implantation may be reflected in a reduced tVSA.

Effects of near-monotonous speech of persons with Parkinson’s disease on listening effort and intelligibility

ABSTRACT The majority of patients with Parkinson’s disease (PD) develop hypokinetic dysarthria with a disturbance of prosody. The most important acoustic characteristic of prosodic impairment in PD is a lack of fundamental frequency (F0)-variability. It is well established that a lack of F0-variability can negatively influence the speech intelligibility of neurotypical speakers in background noise. The purpose of this study was to investigate which aspect of processing speech realised by speakers with PD is affected by lack of intonation: intelligibility as measured by a transcription task, scaled intelligibility and/or perceived listening effort when there is no background noise. F0-flattening of Semantically Unpredictable Sentences (SUS) was achieved, while the natural F0-declination was preserved. This kind of F0-flattening affected scaled intelligibility and perceived listening effort, while transcription performance remained unchanged.

Listener Factors Related to the Perception of Accented Speech

The purpose of this study was to explore the effect of the listener’s education and occupation on intelligibility, comprehensibility (ease of understanding), and accentedness in speakers of Russian-accented American English (RA), Southern-accented American English (SA), and General American English (GAE). Native English listeners ( N=126) rated various aspects of each sample presented via a questionnaire. All aspects of speech other than rate were rated highest in the GAE sample followed by the SA and RA samples. Intonation and fluency aspects of accented speech appeared to be influenced by the differences in educational or occupational backgrounds. The study also discussed additional influential factors for the perception of accented speech such as clarity, accentedness, and acceptability of speech for SLPs. This study contributes to increase the awareness of factors associated with the negative perception of regional and foreign accents.

Comparison of intelligibility measures for children with velopharyngeal insufficiency: visual analog scale ratings, interval scales, and orthographic transcription (OT)-based measures

ABSTRACT Regardless of the underlying cause for speech impairment in speakers with cleft palate, a universal consequence of cleft palate is reduced speech intelligibility. Still, there is no standardised approach for measuring intelligibility for speakers with cleft speech. The current study aimed to determine the relationship between orthographic transcription (OT)-based measures, interval-scale ratings, and visual analog scale (VAS) ratings for perceptual judgements of intelligibility in speakers with cleft palate as judged by speech-language pathologists (SLPs). The speaker participants were six speakers with velopharyngeal insufficiency secondary to cleft palate. Four sets of sentences from the Hearing in Noise Test were recorded from each speaker. A total of 14 SLPs provided their intelligibility judgement on these speaker’s recordings by word-by-word orthographic transcriptions, a visual analog scale (0–100), and a 5-point interval rating scale. A Spearman rank correlation test indicated a negative, strong correlation between OT-based measurements and VAS scores (r = −.94; p = 0.01) and between OT-based measurements and interval rating scores (r = −.77, p = 0.01). A strong, positive correlation was found between scores obtained from VAS and interval rating scales (r = .83, p = 0.05). The strong relationship between the objective measure of intelligibility (i.e. OT-based measure) and a subjective measure of intelligibility (i.e. VAS and interval scale) supports using a less time-consuming VAS as a substitute for orthographic transcription in measuring intelligibility in cleft palate speech.

Effects of multitasker babble noise on speech intelligibility in children with velopharyngeal insufficiency (VPI).

Intelligibility measurement is influenced by the characteristics of a speaker, listener and contextual factors. This study addresses the clinical problem of measuring speech intelligibility in children with velopharyngeal insufficiency (VPI) in real-world conditions. The purpose of the study was to investigate the effects of background noise on speech intelligibility in speakers with velopharyngeal insufficiency (VPI) compared to typical speech. The study further determined the contribution of nasalance and articulation accuracy in judgments of intelligibility. Fifteen speakers diagnosed with VPI and their typical peers provided audio recordings of 20 sentences from the Hearing in Noise Test. Speech samples were presented over quiet and noise (+5dB signal-to-noise ratio) conditions to 70 naïve listeners. Intelligibility scores from naïve listeners' orthographic transcriptions were obtained as the percentage of correctly identified words. A repeated-measures analysis of variance showed diagnosis of VPI (F(1, 28) = 13.44, p = 0.001, and presence of noise (F(1, 28) = 39.18, p < 0.001) significantly affected the intelligibility scores. There was no interaction between the diagnosis of VPI and noise (F(1, 28) = 0.06, p = 0.80). The multivariate regression analysis indicated that nasalance and articulation accuracy explain a significant amount of variance in the intelligibility scores of VPI speakers in quiet (F(2, 12) = 7.11, p < 0.05, R2 = 0.55, R2 Adjusted = 0.47) and noise (F(2, 12) = 6.32, p < 0.05, R2 = 0.51, R2 Adjusted = 0.43), but the significance mainly came from the effect of percentage of consonants correct (β = 0.97, t(12) = 2.90, p = 0.01). Percentage of consonants correct significantly increased the speech intelligibility in either with or without noise conditions. The current work suggests that background noise will significantly affect reductions in intelligibility in both groups; the effect is more prominent in VPI speech. It was also further noted that articulation accuracy significantly affected intelligibility in quiet and noise rather than nasalance scores. What is already known on the subject Intelligibility measurement is influenced by the characteristics of a speaker, listener and contextual factors. Accordingly, it is essential to determine the degree to which speech assessments in the clinic can predict communication difficulties in the presence of background noise in real life. Background noise can adversely cause speech intelligibility degradation in individuals with speech disorders. What this study adds The study examined the effects of background noise on speech intelligibility in speakers with velopharyngeal insufficiency (VPI) secondary to cleft palate compared to typical speech. The study results suggested that the presence of background noise will significantly affect reductions in intelligibility in both groups; however, the effect is more prominent in VPI speech. What are the clinical implications of this work? We found out that the intelligibility of VPI speech is lower in the presence of background noise, and therefore, assessments of speech intelligibility in clinical settings should take this into account. To ensure effective communication in noisy environments, recommended strategies include selecting quiet locations, eliminating potential distractions and supplementing communication with nonverbal cues. It is important to recognize that the effectiveness of these strategies may vary depending on the individual and the specific communication context.

The association between longitudinal declines in speech sound accuracy and speech intelligibility in speakers with amyotrophic lateral sclerosis

ABSTRACT The purpose of this study was to examine how neurodegeneration secondary to amyotrophic lateral sclerosis (ALS) impacts speech sound accuracy over time and how speech sound accuracy, in turn, is related to speech intelligibility. Twenty-one participants with ALS read the Bamboo Passage over multiple data collection sessions across several months. Phonemic and orthographic transcriptions were completed for all speech samples. The percentage of phonemes accurately produced was calculated across each phoneme, sound class (i.e. consonants versus vowels), and distinctive feature (i.e. features involved in Manner of Articulation, Place of Articulation, Laryngeal Voicing, Tongue Height, and Tongue Advancement). Intelligibility was determined by calculating the percentage of words correctly transcribed orthographically by naive listeners. Linear mixed effects models were conducted to assess the decline of each distinctive feature over time and its impact on intelligibility. The results demonstrated that overall phonemic production accuracy had a nonlinear relationship with speech intelligibility and that a subset of features (i.e. those dependent on precise lingual and labial constriction and/or extensive lingual and labial movement) were more important for intelligibility and were more impacted over time than other features. Furthermore, findings revealed that consonants were more strongly associated with intelligibility than vowels, but consonants did not significantly differ from vowels in their decline over time. These findings have the potential to (1) strengthen mechanistic understanding of the physiological constraints imposed by neuronal degeneration on speech production and (2) inform the timing and selection of treatment and assessment targets for individuals with ALS.

Investigating English Pronunciation of Speakers of Asante Twi: A Case of Wesley College of Education Level 100 Students, Ghana

English language pronunciation teaching is typically based on native speakers' norms. English is spoken all over the world. It has become a lingua franca for many people, an international language that ends up promoting successful communication for all. It is a medium of instruction for our learners from Basic Four to the tertiary level. Despite this, English pronunciation presents a lot of difficulties to its users, as it is inconsistent with the spelling of words. The problem exists with speakers of Asante Twi as students of Wesley College of Education who use it as a second language. They make errors in pronouncing some English words. Against this background, this study seeks to assess the pronunciation intelligibility of speakers of English whose first language is Asante Twi. It is worthwhile to identify and analyse their peculiar difficulties and get a specific prescription to correct the errors. The study findings will have significant pedagogical implications for teaching English pronunciation at Wesley College of Education. It will help raise awareness among teacher trainees of the critical problems they are going to face in the future as teachers.

Lexical Characteristics of the Speech Intelligibility Test: Effects on Transcription Intelligibility for Speakers With Multiple Sclerosis and Parkinson's Disease.

Lexical characteristics of speech stimuli can significantly impact intelligibility. However, lexical characteristics of the widely used Speech Intelligibility Test (SIT) are unknown. We aimed to (a) define variation in neighborhood density, word frequency, grammatical word class, and type-token ratio across a large corpus of SIT sentences and tests and (b) determine the relationship of lexical characteristics to speech intelligibility in speakers with multiple sclerosis (MS), Parkinson's disease (PD), and neurologically healthy controls. Using an extant database of 92 speakers (32 controls, 30 speakers with MS, and 30 speakers with PD), percent correct intelligibility scores were obtained for the SIT. Neighborhood density, word frequency, word class, and type-token ratio were calculated and summed for each of the 11 sentences of each SIT test. The distribution of each characteristic across SIT sentences and tests was examined. Linear mixed-effects models were performed to assess the relationship between intelligibility and the lexical characteristics. There was large variability in the distribution of lexical characteristics across this large corpus of SIT sentences and tests. Modeling revealed a relationship between intelligibility and the lexical characteristics, with word frequency and word class significantly contributing to the model. Three primary findings emerged: (a) There was considerable variability in lexical characteristics both within and across the large corpus of SIT tests; (b) there was not a robust association between intelligibility and the lexical characteristics; and (c) findings from a study demonstrating an effect of neighborhood density and word frequency on intelligibility were replicated. Clinical and research implications of the findings are discussed, and three exemplar SIT tests systematically controlling for neighborhood density and word frequency are provided.

Speech intelligibility of English spoken by Indonesian and Taiwanese speakers and judged by Taiwanese listeners: application of TOCS+ automatic software

Former investigations were about the familiarity advantage that people with the same language backgrounds are more intelligible. Besides, particular English was most intelligible to participants with high certain English familiarity. This study investigated how Taiwanese listeners judge the English speech intelligibility of Taiwanese and Indonesian speakers. Thirty Indonesian speakers and thirty Taiwanese speakers participated in this study. Ninety Taiwanese listeners were recruited to judge speech intelligibility. The recording and judging process used the TOCS+ software (Hodge et al., 2009). The software provided 124 contrast items of minimal pairs for the recognition task, including contrast of syllable shape, vowels, and consonants. The listeners' judgments were then analyzed by the TOCS+ software automatically. It was found that Taiwanese English speaker is more intelligible to Taiwanese listeners. The variables that predict intelligibility for Indonesian speakers are syllable shape contrast item correct (SSIC) and consonant item correct (CIC), while Taiwanese speakers’ SSIC and vowel item correct (VIC) did not predict intelligibility. Only CIC predicts intelligibility. Both groups made similar errors in consonant voicing. The study's findings contribute to the teaching materials for the English preparation of students who will study abroad.  Â

Relationships Between Acoustic Characteristics and Intelligibility Scores: A Reanalysis of Japanese Speakers' Productions of American English Liquids.

The primary purpose of this research report was to investigate the relationships between acoustic characteristics and perceived intelligibility for native Japanese speakers' productions of American English liquids. This report was based on a reanalysis of intelligibility scores and acoustic analyses that were reported in two previous studies. We examined which acoustic parameters were associated with higher perceived intelligibility scores for their productions of /l/ and /ɹ/ in American English, and whether Japanese speakers' productions of the two liquids were acoustically differentiated from each other. Results demonstrated that the second formant (F2) was strongly correlated with the perceived intelligibility scores for the Japanese adults' productions. Results also demonstrated that the Japanese adults' and children's productions of /l/ and /ɹ/ were indeed differentiated by some acoustic parameters including the third formant (F3). In addition, some changes occurred in the Japanese children's productions over the course of 1 year. Overall, the present report shows that Japanese speakers of American English may be making a distinction between /l/ and /ɹ/ in production, although the distinctions are made in a different way compared with native English speakers' productions. These findings have implications for setting realistic goals for improving intelligibility of English /l/ and /ɹ/ for Japanese speakers, as well as theoretical advancement of second-language speech learning.

Assessment of L2 intelligibility: Comparing L1 listeners and automatic speech recognition

AbstractAn increasing number of studies are exploring the benefits of automatic speech recognition (ASR)–based dictation programs for second language (L2) pronunciation learning (e.g. Chen, Inceoglu &amp; Lim, 2020; Liakin, Cardoso &amp; Liakina, 2015; McCrocklin, 2019), but how ASR recognizes accented speech and the nature of the feedback it provides to language learners is still largely under-researched. The current study explores whether the intelligibility of L2 speakers differs when assessed by native (L1) listeners versus ASR technology, and reports on the types of intelligibility issues encountered by the two groups. Twelve L1 listeners of English transcribed 48 isolated words targeting the /ɪ-i/ and /æ-ε/ contrasts and 24 short sentences that four Taiwanese intermediate learners of English had produced using Google’s ASR dictation system. Overall, the results revealed lower intelligibility scores for the word task (ASR: 40.81%, L1 listeners: 38.62%) than the sentence task (ASR: 75.52%, L1 listeners: 83.88%), and highlighted strong similarities in the error types – and their proportions – identified by ASR and the L1 listeners. However, despite similar recognition scores, correlations indicated that the ASR recognition of the L2 speakers’ oral productions mirrored the L1 listeners’ judgments of intelligibility in the word and sentence tasks for only one speaker, with significant positive correlations for one additional speaker in each task. This suggests that the extent to which ASR approaches L1 listeners at recognizing accented speech may depend on individual speakers and the type of oral speech.

Clear Speech Variants: An Investigation of Intelligibility and Speaker Effort in Speakers With Parkinson's Disease.

This study investigated the effects of three clear speech variants on sentence intelligibility and speaking effort for speakers with Parkinson's disease (PD) and age- and sex-matched neurologically healthy controls. Fourteen speakers with PD and 14 neurologically healthy speakers participated. Each speaker was recorded reading 18 sentences from the Speech Intelligibility Test in their habitual speaking style and for three clear speech variants: clear (SC; given instructions to speak clearly), hearing impaired (HI; given instructions to speak with someone with a hearing impairment), and overenunciate (OE; given instructions to overenunciate each word). Speakers rated the amount of physical and mental effort exerted during each speaking condition using visual analog scales (averaged to yield a metric of overall speaking effort). Sentence productions were orthographically transcribed by 50 naive listeners. Linear mixed-effects models were used to compare intelligibility and speaking effort across the clear speech variants. Intelligibility was reduced for the PD group in comparison to the control group only in the habitual condition. All clear speech variants significantly improved intelligibility above habitual levels for the PD group, with OE maximizing intelligibility, followed by the SC and HI conditions. Both groups rated speaking effort to be significantly higher for both the OE and HI conditions versus the SC and habitual conditions. For speakers with PD, all clear speech variants increased intelligibility to a level comparable to that of healthy controls. All clear speech variants were also associated with higher levels of speaking effort than habitual speech for the speakers with PD. Clinically, findings suggest that clear speech training programs consider using the instruction "overenunciate" for maximizing intelligibility. Future research is needed to identify if high levels of speaking effort elicited by the clear speech variants affect long-term sustainability of the intelligibility benefit.

Intelligibility of speech produced by sighted and blind adults.

PurposeIt is well known that speech uses both the auditory and visual modalities to convey information. In cases of congenital sensory deprivation, the feedback language learners have access to for mapping visible and invisible orofacial articulation is impoverished. Although the effects of blindness on the movements of the lips, jaw, and tongue have been documented in francophone adults, not much is known about their consequences for speech intelligibility. The objective of this study is to investigate the effects of congenital visual deprivation on vowel intelligibility in adult speakers of Canadian French.MethodTwenty adult listeners performed two perceptual identification tasks in which vowels produced by congenitally blind adults and sighted adults were used as stimuli. The vowels were presented in the auditory, visual, and audiovisual modalities (experiment 1) and at different signal-to-noise ratios in the audiovisual modality (experiment 2). Correct identification scores were calculated. Sequential information analyses were also conducted to assess the amount of information transmitted to the listeners along the three vowel features of height, place of articulation, and rounding.ResultsThe results showed that, although blind speakers did not differ from their sighted peers in the auditory modality, they had lower scores in the audiovisual and visual modalities. Some vowels produced by blind speakers are also less robust in noise than those produced by sighted speakers.ConclusionTogether, the results suggest that adult blind speakers have learned to adapt to their sensory loss so that they can successfully achieve intelligible vowel targets in non-noisy conditions but that they produce less intelligible speech in noisy conditions. Thus, the trade-off between visible (lips) and invisible (tongue) articulatory cues observed between vowels produced by blind and sighted speakers is not equivalent in terms of perceptual efficiency.

Consonant articulation acoustics and intelligibility in Swedish speakers with Parkinson’s disease: a pilot study

ABSTRACT Imprecise consonant articulation is common in speakers with Parkinson’s disease and can affect intelligibility. The research on the relationship between acoustic speech measures and intelligibility in Parkinson’s disease is limited, and most of the research has been conducted on English. This pilot study investigated aspects of consonant articulation acoustics in eleven Swedish speakers with Parkinson’s disease and six neurologically healthy persons. The focus of the study was on consonant cluster production, articulatory motion rate and variation, and voice onset time, and how these acoustic features correlate with speech intelligibility. Among the measures in the present study, typicality ratings of heterorganic consonant clusters /spr/ and /skr/ had the strongest correlations with intelligibility. Measures based on syllable repetition, such as repetition rate and voice onset time, showed varying results with weak to moderate correlations with intelligibility. One conclusion is that some acoustic measures may be more sensitive than others to the impact of the underlying sensory-motor impairment and dysarthria on speech production and intelligibility in speakers with Parkinson’s disease. Some aspects of articulation appear to be equally demanding in terms of acoustic realisation for elderly healthy speakers and for speakers with Parkinson’s disease, such as sequential motion rate measures. Clinically, this would imply that for the purpose of detecting signs of disordered speech motor control, choosing measures with less variation among older speakers without articulation impairment would lead to more robust results.

Speech Impairment in Cerebellar Ataxia Affects Naturalness More Than Intelligibility.

The purpose of this analysis was to document intelligibility and naturalness in ataxia, a neurological condition that results from cerebellar damage. The cerebellum is important for normal speech production to scale and coordinate articulatory and laryngeal movements. The disruption of these cerebellar mechanisms has unique implications for how intelligibility and naturalness are affected in ataxia. The results of research on speech in ataxia have important clinical implications for assessment and treatment of individuals with ataxic dysarthria. Speech samples from 27 participants with ataxia and 28 age- and sex-matched control participants were assessed by nine speech-language pathology graduate students for intelligibility and naturalness. Intelligibility was measured as the percentage of words transcribed correctly, and naturalness was assessed as a subjective rating on a seven-point interval scale. Both intra- and inter-rater reliability were moderate to high for both intelligibility and naturalness. Speech intelligibility and naturalness were robustly decreased in the ataxia group compared to the control group; however, the difference was greater for measures of speech naturalness. There were robust relationships among dysarthria severity, length of diagnosis, and speech naturalness in speakers with ataxia, but there were no other robust effects for age, sex, or impact on quality of life for intelligibility or naturalness. Speech naturalness was more impaired than intelligibility in speakers with ataxia. Impaired naturalness can have debilitating consequences for communicative participation, effectiveness, and quality of life. Assessment and treatment for ataxic dysarthria should include aspects of prosodic control for speech naturalness.

The development of the Language-Independent Speech in Noise and Reverberation test (LISiNaR) and evaluation in listeners with English as a second language

Objective Create a language-independent, ecologically valid auditory processing assessment and evaluate relative stimuli intelligibility in native and non-native English speakers. Design The Language-Independent Speech in Noise and Reverberation Test (LISiNaR) targets comprised consonant-vowel (CVCV) pseudo-words. Distractors comprised CVCVCVCV pseudo-words. Stimuli were presented over headphones using an iPad either face-to-face or remotely. Scoring occurred adaptively to establish a participant’s speech reception threshold in noise (SRT). The listening environment was simulated using reverberant and anechoic head-related transfer functions. In four test conditions, targets originated from 0°. Distractors originated from either ±90°, ±67.5° and ±45° (spatially separated) or 0° azimuth (co-located). Reverberation impact (RI) was calculated as the difference in SRTs between the anechoic and reverberant conditions and spatial advantage (SA) as the difference between the spatially separated and co-located conditions. Study sample Young adult native speakers of Australian (n = 24) and Canadian (25) and non-native English speakers (34). Results No significant effects of language occurred for the test conditions, RI or SA. A small but significant effect of delivery mode occurred for RI. Reverberation impacted SRT by 5 dB relative to anechoic conditions. Conclusion Performance on LISiNaR is not affected by the native language or accent of groups tested in this study.

Validity of Off-the-Shelf Automatic Speech Recognition for Assessing Speech Intelligibility and Speech Severity in Speakers With Amyotrophic Lateral Sclerosis.

There is increasing interest in using automatic speech recognition (ASR) systems to evaluate impairment severity or speech intelligibility in speakers with dysarthria. We assessed the clinical validity of one currently available off-the-shelf (OTS) ASR system (i.e., a Google Cloud ASR API) for indexing sentence-level speech intelligibility and impairment severity in individuals with amyotrophic lateral sclerosis (ALS), and we provided guidance for potential users of such systems in research and clinic. Using speech samples collected from 52 individuals with ALS and 20 healthy control speakers, we compared word recognition rate (WRR) from the commercially available Google Cloud ASR API (Machine WRR) to clinician-provided judgments of impairment severity, as well as sentence intelligibility (Human WRR). We assessed the internal reliability of Machine and Human WRR by comparing the standard deviation of WRR across sentences to the minimally detectable change (MDC), a clinical benchmark that indicates whether results are within measurement error. We also evaluated Machine and Human WRR diagnostic accuracy for classifying speakers into clinically established categories. Human WRR achieved better accuracy than Machine WRR when indexing speech severity, and, although related, Human and Machine WRR were not strongly correlated. When the speech signal was mixed with noise (noise-augmented ASR) to reduce a ceiling effect, Machine WRR performance improved. Internal reliability metrics were worse for Machine than Human WRR, particularly for typical and mildly impaired severity groups, although sentence length significantly impacted both Machine and Human WRRs. Results indicated that the OTS ASR system was inadequate for early detection of speech impairment and grading overall speech severity. While Machine and Human WRR were correlated, ASR should not be used as a one-to-one proxy for transcription speech intelligibility or clinician severity ratings. Overall, findings suggested that the tested OTS ASR system, Google Cloud ASR, has limited utility for grading clinical speech impairment in speakers with ALS.