Systematic Review of Literature on Speech Intelligibility and Classroom Acoustics in Elementary Schools.

PURPOSE: Good verbal signals and low background noise are key factors for all children to maximize understanding of what is being taught. Classroom shape, surroundings, and even furnishings change how the environment "sounds" and how speech is "heard" in the classroom. Classroom acoustics is perhaps one of the most important, but often least considered, factors when designing a classroom. This systematic review aimed to characterize the relationship between intelligibility of speech and room acoustics in elementary schools based on the available evidence. METHOD: Eligible studies were identified using two computerized databases: PubMed and Scopus. In total, 23 publications met our inclusion criteria: (a) Participants must have been from elementary schools, (b) acoustic characterization of the classroom must have been provided, (c) intelligibility tests must have been performed, and (d) articles were written in English. RESULTS: After identifying the parameters and tests used to quantify the intelligibility of speech, the speech intelligibility scores were analyzed in relation with acoustical parameters found in the articles, particularly signal-to-noise ratio and speech transmission index. Our results highlighted the negative effect on intelligibility associated with poor transmission of the speech and poor classroom acoustics caused by long reverberation times and high background noise. CONCLUSION: Good classroom acoustics is needed to improve speech intelligibility and, therefore, increase children's academic success.

The Formant Bandwidth as a Measure of Vowel Intelligibility in Dysphonic Speech.

OBJECTIVE: The current paper examined the impact of dysphonia on the bandwidth of the first two formants of vowels, and the relationship between the formant bandwidth and vowel intelligibility. METHODS: Speaker participants of the study were 10 adult females with healthy voice and 10 adult females with dysphonic voice. Eleven vowels in American English were recorded in /h/-vowel-/d/ format. The vowels were presented to 10 native speakers of American English with normal hearing, who were asked to select a vowel they heard from a list of /h/-vowel-/d/ words. The vowels were acoustically analyzed to measure the bandwidth of the first and second formants (B1 and B2). Separate Wilcoxon rank sum tests were conducted for each vowel for normal and dysphonic speech because the differences in B1 and B2 were found to not be normally distributed. Spearman correlation tests were conducted to evaluate the association between the difference in formant bandwidths and vowel intelligibility between the healthy and dysphonic speakers. RESULTS: B1 was significantly greater in dysphonic vowels for seven of the eleven vowels, and lesser for only one of the vowels. There was no statistically significant difference in B2 between the normal and dysphonic vowels, except for the vowel /i/. The difference in B1 between normal and dysphonic vowels strongly predicted the intelligibility difference. CONCLUSION: Dysphonia significantly affects B1, and the difference in B1 may serve as an acoustic marker for the intelligibility reduction in dysphonic vowels. This acoustic-perceptual relationship should be confirmed by a larger-scale study in the future.

The Effect of Bilingualism on Production and Perception of Vocal Fry.

AIMS: (1) Determine the difference in vocal fry phonation in English and Spanish productions among bilingual young adults, (2) Characterize the effect of spoken language and native language on vocal fry production among English-Spanish bilingual speakers, (3) Identify the effect of first and second language knowledge of the listener in the voice perceptual assessment, and (4) Define the effect of the environment of the assessment (in situ vs. online), in the voice perceptual assessment. METHOD: Exploratory cross-sectional study of 34 bilingual (Spanish-English) speakers and six inexperienced listeners. Participating speakers produced two speech samples (one in English and one in Spanish). Six inexperienced monolingual and bilingual listeners performed the voice perceptual assessment of vocal fry, General grade of hoarseness, and Roughness using a 4-point rating scale. RESULTS: Bilingual speakers used vocal fry more often when they were speaking in English (around 3%) compared with their production in Spanish (around 2%). Bilingual native English speakers used vocal fry more often during their productions in both languages compared with bilingual native Spanish speakers. Bilingual listeners had the highest agreement when identifying vocal fry in both languages. CONCLUSIONS: Differences in production of vocal fry between native speakers of American English and native speakers of Spanish may be evidence of transferring of vocal behavior (such as vocal fry) from one language to the second one. In addition, being a bilingual listener may have an important effect on the perceptual identification of voice quality in English and Spanish, as well as vocal fry in English.

The Effects of Reading Speed on Acoustic Voice Parameters and Self-reported Vocal Fatigue in Students.

INTRODUCTION: Vocal loading tasks (VLTs) help researchers gather acoustic measurements and understand how a healthy speaker adjusts their voice in response to challenges. There is a dearth of evidence measuring the impact of speaking rate in VLTs on acoustic voice parameters and vocal fatigue. OBJECTIVES: In the present study, the relationships between acoustic voice parameters and self-reported vocal fatigue were examined through an experimental VLT. METHODS: 38 students completed a 45-minute VLT which involved the recording of three randomized reading tasks. The tasks varied by the speed in which the words were presented (slow, medium, fast) on a computer monitor. Vocal fatigue ratings were measured subjectively using a Borg scale and negative adaptations to vocal loading were measured objectively using Sound Pressure Level (SPL, in dBA), fundamental frequency (fo, in semitones), and phonation time (Dt %). RESULTS: Analysis indicated that vocal fatigue increases with time, and the slope of this relationship is affected by the speaking rate. SPL and fo increased with speaking rate and the standard deviation of SPL and fo decreased with speaking rate. On average, the male participants' phonation time values were 7.8% lower than the female participants. The rate of increase of vocal fatigue with time during the experiment was higher in the fast speaking style compared to the slow and medium ones. CONCLUSION: The results provide support that the novel VLT altered multiple vocal parameters to induce measurable changes in vocal fatigue.

Do Voice Acoustic Parameters Differ Between Bilingual English-Spanish Speakers and Monolingual English Speakers During English Productions?

BACKGROUND: In addition to language differences in fundamental frequency between bilinguals and monolinguals, studies have also included other acoustic parameters to analyze differences in voice production associated with the language spoken. AIM: To identify differences in voice acoustic parameters during English productions between monolingual and bilingual English speakers. METHOD: Exploratory cross-sectional study with two groups of subjects: monolingual English speakers (n = 40), and bilingual English-Spanish speakers (n = 13). Participants filled out a questionnaire and recorded one reading in English (second sentence of Rainbow passage "The rainbow is a division of white light into many beautiful colors") under a "virtual-simulated" acoustic condition of No Noise and Medium Reverberation Time (0.8 seconds). RESULT: Analysis by gender shows that monolingual speakers had higher fundamental frequency mode, and lower standard deviation of fundamental frequency compared to bilingual English-Spanish speakers. Bilingual male speakers had higher jitter and harmonics-to-noise ratio than monolingual speakers. On the contrary, female bilingual speakers had lower jitter and shimmer than monolingual speakers. CONCLUSIONS: Speaking a second language may influence voice acoustic parameters, and therefore, should be considered when comparing acoustic speech metrics.

Singing Voice Quality: The Effects of Maxillary Dental Arch and Singing Style.

INTRODUCTION: In classical singing techniques, it is common to manipulate the vocal tract to channel airflow to increase voice quality and volume. Technique varies according to the style of the music, the voice type, and range of a given singer. Although these practices are intentional, fixed physiological aspects of a singer's vocal instrument also play an extremely impactful role in determining voice quality. OBJECTIVES: In the present study, the relationship between the dimensions of the maxillary dental arch and voice quality were examined in professional singers. METHODS: The dimensions of the palate were measured from the maxillary dental casts of 14 female singers. Audio recordings were made for the same participants while singing a sustained /a/ singing vowel, a glissando, the song "Are You Sleeping", and a selected song from their personal repertoire. The dimensions of the palate were measured from maxillary dental casts. From the recordings, two parameters were calculated: (1) the Singing Power Ratio (SPR) and (2) A2 A1 ratio. Higher SPR values indicate a stronger ring in the voice, typical of operatic singing style, while higher A2 A1 ratio values are associated with the belting singing style. RESULTS: Singers with larger frontal palate depth, smaller posterior palate depth, larger frontal palate width, and smaller posterior palate width seem to be more suitable for an operatic singing style. Singers who had larger overall depth and width of the palate measurements produced an increased second harmonic, typical of the belting style. CONCLUSIONS: When considering a singer's ability to produce vocalizations successfully, physiological structure is an increasingly important factor. The present study discovered that palate depth and width are associated with statistically significant differences in SPR and A2/A1 parameters. These parameters correlate with two styles of singing, operatic, and belting respectively.

Agreement between Transcription- and Rating-Based Intelligibility Measurements for Evaluation of Dysphonic Speech in Noise.

Dysphonia negatively affects a speaker's intelligibility, especially in noisy environments. Previously, our study showed this effect of dysphonia with the transcription-based intelligibility measurement. While this finding indicates the importance of intelligibility assessment for this population, implementing the transcription-based measurement may be difficult in clinical settings due to its resource-demanding nature. Using the same speakers, this study examined the agreement between transcription- and rating-based intelligibility measurements. Six sentences from the Consensus of Auditory-Perceptual Evaluation of Voice (CAPE-V) were recorded from 18 individuals with dysphonia (6 adult females, 6 adult males, and 6 children). Their dysphonia severity was determined through auditory-perceptual evaluation by two speech-language pathologists. Cafeteria noise was added to these recordings at SNR0 and paired with a sample from a healthy speaker in their age and/or gender group. Forty-five listeners rated intelligibility of the dysphonic samples on a 7-point rating scale. Spearman's rank correlation tests were conducted to examine the correlations between rating-based intelligibility measurement and the transcription-based measurement from our previous study, as well as the voice quality ratings and the rating-based intelligibility measurements. There was a strong positive correlation between the transcription- and rating-based measurements at all noise levels. The correlation between rating-based intelligibility measurement and breathiness rating was also strong. Our findings suggest that the rating-based intelligibility measurement could potentially be used as a substitute for the transcription-based analysis. Furthermore, the intelligibility deficit may be particularly problematic to patients who present with breathy dysphonia.