Automatic Pathological Speech Intelligibility Assessment Exploiting Subspace-Based Analyses

The purpose of this study was twofold: (a) to determine the extent to which 4-channel, slow-acting wide dynamic range amplitude compression (WDRC) can counteract the perceptual effects of reduced auditory dynamic range and (b) to examine the relation between objective measures of speech intelligibility and categorical ratings of speech quality for sentences processed with slow-acting WDRC. Multiband expansion was used to simulate the effects of elevated thresholds and loudness recruitment in normal hearing listeners. While some previous studies have shown that WDRC can improve both speech intelligibility and quality, others have found no benefit. The current experiment shows that moderate amounts of compression can provide a small but significant improvement in speech intelligibility, relative to linear amplification, for simulated-loss listeners with small dynamic ranges (i.e., flat, moderate hearing loss). This benefit was found for speech at conversational levels, both in quiet and in a background of babble. Simulated-loss listeners with large dynamic ranges (i.e., sloping, mild-to-moderate hearing loss) did not show any improvement. Comparison of speech intelligibility scores and subjective ratings of intelligibility showed that listeners with simulated hearing loss could accurately judge the overall intelligibility of speech. However, in all listeners, ratings of pleasantness decreased as the compression ratio increased. These findings suggest that subjective measures of speech quality should be used in conjunction with either objective or subjective measures of speech intelligibility to ensure that participant-selected hearing aid parameters optimize both comfort and intelligibility.

Speech intelligibility and prosody production in children with cochlear implants

Speech intelligibility is usually assessed using subjective tests, but several objective measures of speech intelligibility have also been proposed. This study compares intelligibility of IEEE sentences in collocated speech-shaped noise, recorded through a low-cost amplifier and three current-issue NHS hearing aids with single-channel noise reduction settings switched on and off. Results from twenty-one normal hearing listeners indicates that single-channel noise reduction algorithms can significantly improve intelligibility of noisy speech (p < 0.05), but no differences can be seen between different hearing aid models currently available on the NHS. The low-cost, off-the shelf hearing amplifier performed significantly worse than the NHS prescribed devices. Three objective speech intelligibility measures were applied to the recordings. None of the objective metrics was found to accurately predict the outcomes seen in this study for all hearing aid conditions, though general trends can be predicted (r = 0.83 overall, but for any discrete signal-to-noise ratio across all conditions, maximum r = 0.64). Machine-learning approaches were used to refit parameters from the best performing of these metrics. Although performance was improved, problems in predicting particular conditions remain, suggesting that objective measures do not encompass all relevant factors. [Action on Hearing Loss (England/Wales Registered Charity Number 207720).]

Speech intelligibility is currently measured by scoring how well a person can identify a speech signal. The results of such behavioral measures reflect neural processing of the speech signal, but are also influenced by language processing, motivation, and memory. Very often, electrophysiological measures of hearing give insight in the neural processing of sound. However, in most methods, non-speech stimuli are used, making it hard to relate the results to behavioral measures of speech intelligibility. The use of natural running speech as a stimulus in electrophysiological measures of hearing is a paradigm shift which allows to bridge the gap between behavioral and electrophysiological measures. Here, by decoding the speech envelope from the electroencephalogram, and correlating it with the stimulus envelope, we demonstrate an electrophysiological measure of neural processing of running speech. We show that behaviorally measured speech intelligibility is strongly correlated with our electrophysiological measure. Our results pave the way towards an objective and automatic way of assessing neural processing of speech presented through auditory prostheses, reducing confounds such as attention and cognitive capabilities. We anticipate that our electrophysiological measure will allow better differential diagnosis of the auditory system, and will allow the development of closed-loop auditory prostheses that automatically adapt to individual users.

Identifying the severity level of unintelligibility objectively and efficiently holds critical clinical implications for speech assessment and intervention needs. The speech of children who demonstrate phonological deviations is frequently unintelligible. The use of an accurate and time-efficient measurement of intelligibility is necessary to screen children who may be producing phonological patterns that contribute to significantly reduced intelligibility in connected speech. The purpose of this study was to investigate the degree of concurrent validity between scores received on the 1-Minute Measure of Homonymy and Intelligibility (Hodson, 1992) and speech intelligibility as measured by the percent of words understood in connected speech. For this investigation, intelligibility is operationally defined as the percent of words understood in a connected speech sample derived from orthographic transcription. Data collected were from 48 children, aged 4:0 to 5:6, who demonstrated varying levels of phonological proficiency/deficiency. A group of four listeners who had experience treating children with phonological disorders were responsible for completing orthographic transcriptions of the 48 connected speech samples. The two methods of assessing speech intelligibility investigated in this study were found to correlate highly (r = .84). This is considered a significant statistical correlation and therefore the 1-Minute Measure may be used to provide speech-language pathologists with valuable information to predict a child's intelligibility level in connected speech. A regression formula was employed to predict percentage of intelligibility when presented with a child's 1-Minute Measure score. Results from this correlational study suggest that the 1-Minute Measure of Homonymy and Intelligibility may serve as an assessment tool that can provide a speech-language pathologist with some valuable information pertaining to a child's level of intelligibility in connected speech. When used with another speech assessment tool, the 1-Minute Measure may function as a screening measure to identify preschoolers who produce phonological deviations that interfere with intelligibility of conversational speech.

For this project, different large lecture halls were analyzed using various speech intelligibility measurement techniques. The goal was to determine how well these measurements correlate with each other and convey speech intelligibility. Objective speech intelligibility and other related acoustical measurements were made throughout each hall at varying distances from the speaker. These measurements were repeated in each hall in a standardized manner, allowing the results from the different halls to be compared effectively. These objective measurements were related to the subjective analysis of the hall to determine which measurements indicate an appropriate speech intelligibility level for that space. Background mechanical system noise was introduced into some of the halls to determine the effect on speech intelligibility. Some of the halls tested were modeled in an architectural acoustics computer program to determine how well the actual measurements correlate with the predicted measurements. Measurement techniques and results of the study will be presented.

EnAbstract Background Improved articulatory placement through speech therapy may eliminate compensatory errors, improve velopharyngeal function, minimize perception of hypernasality, and improve speech intelligibility. Aim The aim of this work was to study the effect of preoperative speech therapy on the speech intelligibility in patients with residual velopharyngeal insufficiency in order to provide a better speech outcome in such patients. Patients and methods This study included 41 patients diagnosed with residual velopharyngeal insufficiency after cleft palate repair. Patients were divided into two groups: group I included 22 patients scheduled to undergo speech therapy 6 months preoperatively, and group II included 19 patients who did not receive preoperative speech therapy. Both groups underwent speech therapy for 6 months postoperatively. Evaluation was carried out through auditory perceptual assessment (APA) including the type and degree of open nasality, consonant precision, compensatory articulatory mechanisms (glottal articulation and pharyngealization of fricatives), audible nasal emission of air, and overall intelligibility of speech. All these elements are graded along a five-point scale in which 0 is normal and 4 is severe affection. Documentation of APA is performed by high fidelity speech and voice audio recording and endoscopy. Formal speech intelligibility testing was carried out using the Arabic Speech Intelligibility test, which is designed to provide an estimation of the overall speech intelligibility of children by providing a total score in percentage. Nasometry was performed for all patients using a Kay nasometer, which provides the ‘nasalance score’. Results On comparing the APA assessment of group I after 6 months of speech therapy postoperatively with the preoperative data, a highly significant decrease with regard to all parameters was revealed; however, in group II, the same comparison revealed a highly significant decrease as regards the degree of open nasality and nasal emission of air and a significant difference in terms of glottal articulation, pharyngealization of fricatives, and overall speech intelligibility. On comparing the two groups postoperatively, a significant difference in glottal articulation, pharyngealization of fricatives, and overall speech intelligibility, being more improved in group I, was revealed. Nasometry showed a significant difference between the postoperative results after speech therapy compared with the preoperative results, with a nonsignificant difference between the two groups postoperatively. In group I, the results of the Arabic Speech Intelligibility test showed a highly significant decrease in the number of patients with unintelligible speech and poor speech intelligibility, a significant decrease in number of patients with fair speech intelligibility, and a highly significant increase in the number of patients with good and excellent speech intelligibility. In group II, there was a significant decrease in the number of patients with unintelligible speech and poor speech intelligibility and a significant increase in the number of patients with fair, good, and excellent speech intelligibility. Conclusion and recommendations Speech therapy before surgery for residual velopharyngeal insufficiency can improve the results of postoperative therapy, with a better speech intelligibility outcome. Therefore, it is recommended to schedule a speech therapy program before secondary repair of the velopharyngeal valve in order to attain better speech intelligibility.

The present study investigated the development of audiovisual comprehension skills in prelingually deaf children who received cochlear implants. We analyzed results obtained with the Common Phrases (Robbins et al., 1995) test of sentence comprehension from 80 prelingually deaf children with cochlear implants who were enrolled in a longitudinal study, from pre-implantation to 5 years after implantation. The results revealed that prelingually deaf children with cochlear implants performed better under audiovisual (AV) presentation compared with auditory-alone (A-alone) or visual-alone (V-alone) conditions. AV sentence comprehension skills were found to be strongly correlated with several clinical outcome measures of speech perception, speech intelligibility, and language. Finally, pre-implantation V-alone performance on the Common Phrases test was strongly correlated with 3-year postimplantation performance on clinical outcome measures of speech perception, speech intelligibility, and language skills. The results suggest that lipreading skills and AV speech perception reflect a common source of variance associated with the development of phonological processing skills that is shared among a wide range of speech and language outcome measures.

The purpose of this study was to describe normative and validation data on the Intelligibility in Context Scale (ICS; McLeod, Harrison, & McCormack, 2012c) for English-speaking children. The ICS is a 7-item, parent-report measure of children's speech intelligibility with a range of communicative partners. Data were collected from the parents of 803 Australian English-speaking children ranging in age from 4;0 (years;months) to 5;5 (37.0% were multilingual). The mean ICS score was 4.4 (SD = 0.7) out of a possible total score of 5. Children's speech was reported to be most intelligible to their parents, followed by their immediate family, friends, and teachers; children's speech was least intelligible to strangers. The ICS had high internal consistency (α = .94). Significant differences in scores were identified on the basis of sex and age but not on the basis of socioeconomic status or the number of languages spoken. There were significant differences in scores between children whose parents had concerns about their child's speech (M = 3.9) and those who did not (M = 4.6). A sensitivity of .82 and a specificity of .58 were established as the optimal cutoff. Test-retest reliability and criterion validity were established for 184 children with a speech sound disorder. There was a significant low correlation between the ICS mean score and percentage of phonemes correct (r = .30), percentage of consonants correct (r = .24), and percentage of vowels correct (r = .30) on the Diagnostic Evaluation of Articulation and Phonology (Dodd, Hua, Crosbie, Holm, & Ozanne, 2002). Thirty-one parents completed the ICS related to English and another language spoken by their child with a speech sound disorder. The significant correlations between the scores suggest that the ICS may be robust between languages. This article provides normative ICS data for English-speaking children and additional validation of the psychometric properties of the ICS. The robustness of the ICS was suggested because mean ICS scores were not affected by socioeconomic status, number of languages spoken, or whether the ICS was completed in relation to English or another language. The ICS is recommended as a screening measure of children's speech intelligibility.

Intelligibility of speech produced during simultaneous communication

Neural envelope tracking predicts speech intelligibility and hearing aid benefit in children with hearing loss

Nonintrusive objective measurement of speech intelligibility: A review of methodology

Many objective measures have been reported to predict speech intelligibility in noise, most of which were designed and evaluated with English speech corpora. Given the different perceptual cues used by native listeners of different languages, examining whether there is any language effect when the same objective measure is used to predict speech intelligibility in different languages is of great interest, particularly when non-linear noise-reduction processing is involved. In the present study, an extensive evaluation is taken of objective measures for speech intelligibility prediction of noisy speech processed by noise-reduction algorithms in Chinese, Japanese, and English. Of all the objective measures tested, the short-time objective intelligibility (STOI) measure produced the most accurate results in speech intelligibility prediction for Chinese, while the normalized covariance metric (NCM) and middle-level coherence speech intelligibility index ( CSIIm) incorporating the signal-dependent band-importance functions (BIFs) produced the most accurate results for Japanese and English, respectively. The objective measures that performed best in predicting the effect of non-linear noise-reduction processing in speech intelligibility were found to be the BIF-modified NCM measure for Chinese, the STOI measure for Japanese, and the BIF-modified CSIIm measure for English. Most of the objective measures examined performed differently even under the same conditions for different languages.

Objective. Currently, only behavioral speech understanding tests are available, which require active participation of the person being tested. As this is infeasible for certain populations, an objective measure of speech intelligibility is required. Recently, brain imaging data has been used to establish a relationship between stimulus and brain response. Linear models have been successfully linked to speech intelligibility but require per-subject training. We present a deep-learning-based model incorporating dilated convolutions that operates in a match/mismatch paradigm. The accuracy of the model’s match/mismatch predictions can be used as a proxy for speech intelligibility without subject-specific (re)training. Approach. We evaluated the performance of the model as a function of input segment length, electroencephalography (EEG) frequency band and receptive field size while comparing it to multiple baseline models. Next, we evaluated performance on held-out data and finetuning. Finally, we established a link between the accuracy of our model and the state-of-the-art behavioral MATRIX test. Main results. The dilated convolutional model significantly outperformed the baseline models for every input segment length, for all EEG frequency bands except the delta and theta band, and receptive field sizes between 250 and 500 ms. Additionally, finetuning significantly increased the accuracy on a held-out dataset. Finally, a significant correlation (r = 0.59, p = 0.0154) was found between the speech reception threshold (SRT) estimated using the behavioral MATRIX test and our objective method. Significance. Our method is the first to predict the SRT from EEG for unseen subjects, contributing to objective measures of speech intelligibility.

Verifying two commercial software implementations of impulse-response-based speech intelligibility measurements