The influence of clear speech on auditory-perceptual judgments of electrolaryngeal speech

The Effect of Clear Speech on Cantonese Alaryngeal Speakers' Intelligibility

Background/Aim:

The purpose of this study was to provide preliminary data concerning the effect of clear speech (CS) on Cantonese alaryngeal speakers’ intelligibility.

Methods:

Voice recordings of 11 sentences randomly selected from the Cantonese Sentence Intelligibility Test (CSIT) were obtained from 31 alaryngeal speakers (9 electrolarynx [EL] users, 10 esophageal speakers and 12 tracheoesophageal [TE] speakers) in habitual speech (HS) and CS. Two naïve listeners orthographically transcribed a total of 1,364 sentences.

Results:

Significant effects of speaking condition on speaking rate and CSIT scores were observed, but no significant effect of alaryngeal communication methods was noted. CS was significantly slower than HS by 0.78 syllables/s. Esophageal speakers demonstrated the slowest speech rate when using CS, while EL users demonstrated the largest decrease in speaking rate when using CS compared to HS. TE speakers had the highest CSIT scores in HS (listener 1 = 81.4%; listener 2 = 81.3%), and esophageal speakers had the highest CSIT scores in CS (listener 1 = 87.5%; listener 2 = 89.7%). EL users experienced the largest increase in intelligibility while using CS compared to HS (9.1%) followed by esophageal speakers (8.9%) and TE speakers (1.4%).

Conclusion:

Preliminary data indicate that CS may significantly affect Cantonese alaryngeal speakers’ speaking rate and intelligibility. However, intelligibility appeared to vary considerably across speakers. Further research involving larger, heterogeneous groups of speakers and listeners alongside longer and more refined CS training protocols should be conducted to confirm that CS can improve Cantonese alaryngeal speakers’ intelligibility.

Surface Electromyography-Based Recognition, Synthesis, and Perception of Prosodic Subvocal Speech

Purpose This study aimed to evaluate a novel communication system designed to translate surface electromyographic (sEMG) signals from articulatory muscles into speech using a personalized, digital voice. The system was evaluated for word recognition, prosodic classification, and listener perception of synthesized speech. Method sEMG signals were recorded from the face and neck as speakers with (n = 4) and without (n = 4) laryngectomy subvocally recited (silently mouthed) a speech corpus comprising 750 phrases (150 phrases with variable phrase-level stress). Corpus tokens were then translated into speech via personalized voice synthesis (n = 8 synthetic voices) and compared against phrases produced by each speaker when using their typical mode of communication (n = 4 natural voices, n = 4 electrolaryngeal [EL] voices). Naïve listeners (n = 12) evaluated synthetic, natural, and EL speech for acceptability and intelligibility in a visual sort-and-rate task, as well as phrasal stress discriminability via a classification mechanism. Results Recorded sEMG signals were processed to translate sEMG muscle activity into lexical content and categorize variations in phrase-level stress, achieving a mean accuracy of 96.3% (SD = 3.10%) and 91.2% (SD = 4.46%), respectively. Synthetic speech was significantly higher in acceptability and intelligibility than EL speech, also leading to greater phrasal stress classification accuracy, whereas natural speech was rated as the most acceptable and intelligible, with the greatest phrasal stress classification accuracy. Conclusion This proof-of-concept study establishes the feasibility of using subvocal sEMG-based alternative communication not only for lexical recognition but also for prosodic communication in healthy individuals, as well as those living with vocal impairments and residual articulatory function. Supplemental Material https://doi.org/10.23641/asha.14558481.

Variability of Electrolaryngeal Speech Intelligibility in Multitalker Babble

Purpose The purpose of this study was to report the variability of electrolarynx (EL) users' speech intelligibility in quiet and in multitalker babble. Method Ten EL users (five Servox® Digital, five TruTone™) who were at least 2 years postlaryngectomy provided recordings of five sentences from the 1965 Revised List of Phonetically Balanced Sentences. Recordings were judged by two groups of naïve listeners in quiet and in the presence of multitalker babble. Fifteen listeners orthographically transcribed a total of 750 sentences containing 3,750 key words in quiet, and another 15 listeners orthographically transcribed the same sentences mixed with multitalker babble. Results Significant differences in speech intelligibility were observed between listening conditions; 17.9% more key words were correctly identified in quiet compared to multitalker babble. Significant differences in fundamental frequency (F₀) standard deviation and range but not speech intelligibility were observed between EL device types. A positive correlation of moderate significance was observed between F₀ standard deviation and intelligibility for TruTone users in multitalker babble. Conclusions Findings suggest that listeners are able to identify a significantly higher percentage of EL users' speech in quiet compared to multitalker babble, but a large variability in EL users' speech intelligibility exists. Continued investigation involving a larger number of EL users is necessary to confirm this study's findings. Future research should explore the relationships among F₀ measures, speaker characteristics (e.g., rate of speech, articulatory precision), and speech intelligibility, in addition to improving alaryngeal rehabilitation training protocols for EL users.