Toward occupational safety criteria for vocalization

Vocal Fold Vibratory Dose and Perceived Exertion Responses to the Fluid Interval Test for Voice (FIT-V): A Novel Vocal Loading Task Platform

INTRODUCTION

Vocal loading tasks are often used to study how specific variables influence downstream vocal effort or fatigue. The current study introduces a novel vocal loading task, the Fluid Interval Test for Voice (FIT-V) that combines laryngeal diadochokinesis, intervallic rest and exercise, and fluid back pressure. To assess the differences between this novel task and existing vocal loading tasks, we measured vocal fold vibratory dose and perceived phonatory exertion across three 30-minute task conditions: a control loud oral reading task (LOR), a back pressure-resisted Fluid Interval Test for Voice (FIT-V5), and an unresisted Fluid Interval Test for Voice (FIT-V0).

METHODS

Following a training session, 30 participants completed the three tasks (LOR, FIT-V0, and FIT-V5) in counterbalanced order on different days. Vocal fold cycle (Aim 1A) and distance doses (Aim 1B) were collected continuously using a dosimeter. The overall perceived phonatory exertion (Aim 2A) was rated once per minute, while anatomically localized cognitive, laryngeal, thoracic, abdominal, and articulatory exertion (Aim 2B) were rated once at the end of each task. Statistical analyses examined the effects of task and task× time interactions on the dependent variables.

RESULTS

The FIT-V0 and FIT-V5 tasks imposed smaller vocal fold cycle doses (P < 0.001; Aim 1A) and distance doses (P < 0.001; Aim 1B) than the LOR task while eliciting comparable or greater magnitudes of overall perceived phonatory exertion (P = 0.003; Aim 2A). However, anatomically localized perceived exertion was greater in the abdomen and thorax (P < 0.05) and lesser in the anterior neck (P < 0.05) in the two FIT-V tasks relative to the LOR task (Aim 2B). Absolute forced vital capacity was a significant predictor of most forms of anatomically localized perceived exertion.

DISCUSSION

The unresisted FIT-V0 and the back pressure-resisted FIT-V5 tasks yielded similar profiles of overall perceived phonatory exertion, despite vocal fold vibratory doses roughly half that of the LOR task. However, the anatomically localized perceived exertion data underscored subtle across-task differences not apparent in the overall ratings, suggesting potentially distinct physiological and perceptual niches for the three task protocols.

Laryngeal Taping as a Supportive Tool to Relieve Phonasthenia in Singers: A Preliminary Report

AIM

This report aims to perform a preliminary evaluation of the role of taping in the improvement of phonasthenia among professional voice users. The larynx is a vital organ but also a work instrument for many people. Prevention of erroneous use of the vocal mechanism is essential for an optimal voice performance.

METHODS

Nineteen singers complaining voice fatigue underwent taping application in peri-laryngeal areas of the anterior neck for 10 days. Taping effects were estimated by the evaluation of voice analysis parameters (jitter, shimmer, noise to harmonic ratio and singing power ratio) performed in M1 and M2 mechanisms with PRAAT software before and after treatment. In addition, a subjective assessment of phonasthenia was performed using a self-administrated questionnaire.

RESULTS

Statistically significant reduction of Jitter% in M1 (P = 0.021) was reported at the end of treatment; also, an improvement of NHR in M2 was found immediately after the application (P = 0.012) and after 10 days (P = 0.002). These outcomes suggest possible beneficial effects of laryngeal taping on relieving voice fatigue, and therefore improving voice quality. Self-assessment results are consistent with this finding.

CONCLUSION

Since the application of muscular taping in phoniatrics is still in its early stage, further studies and in particular a standardized protocol of application, could facilitate the spread of this technique, also offering help in comparing results.

Potential Biophysiological Mechanisms Underlying Vocal Demands and Vocal Fatigue

Patients with complaint of vocal fatigue have perceptual, acoustic, and aerodynamic outcomes that are heterogeneous in nature. One reason may be due to different underlying biophysiological mechanisms that lead to these heterogeneous clinical presentations. Five potential mechanisms are proposed: neuromuscular, metabolic, vocal tissue, afferent, and central neural. Analytical frameworks and study designs to study these mechanisms are also addressed. A better understanding of biophysiological mechanisms of vocal fatigue can improve precision of therapeutic approaches. It can also help shift management from symptom-based to etiology-focused approaches for vocal fatigue.

Multiparametric analysis of voice following prolonged voice use and voice rest in teachers: evidence from discriminant analysis

PURPOSE

Even though recent investigations have used multiparametric protocol, the set of robust parameters in determining the effects of vocal fatigue and voice rest in teachers is not clear. The first objective of the study was to document the impact of prolonged voice use and voice rest on the subjective and objective voice parameters among Indian secondary school teachers. The second objective was to determine the set voice parameters sensitive to vocal changes resulting from continuous voice use and voice rest.

METHOD

The study included 15 male and 15 female secondary school teachers with a clinically normal voice and no history of voice disorders. Phonation samples were recorded in three different conditions, i.e., condition 1 (before voice use), condition 2 (following voice use), and condition 3 (following voice rest). The vocal Fatigue Index (version 2) was administered before the voice recordings in all three conditions. The objective parameters, namely fundamental frequency, range of fundamental frequency, jitter (%), shimmer (%), harmonic to noise ratio, and smoothened cepstral peak prominence, were extracted.

RESULTS

Results revealed that fundamental frequency, jitter, shimmer, Harmonic to noise ratio, and smoothened cepstral peak prominence were significantly different across the three conditions. The discriminant analysis revealed that only three parameters classified 98.3% of samples accurately between the three conditions.

CONCLUSION

Further research on the correlation between the other subjective and the objective parameters of voice after vocal fatigue would provide more penetrating and ample in-depth insights into the assessment and quantification of vocal fatigue.

Comparison of vocal fatigue and vocal tract discomfort between teachers of normal pupils and teachers of mentally disabled pupils

PURPOSE

This study aims to study the comparison of vocal fatigue and vocal tract discomfort between teachers of normal pupils and teachers of mentally disabled pupils.

STUDY DESIGN

Cross-sectional study METHODS: Participants were 179 teachers (50 male, 129 female) and 30 non-teachers (14 male, 16 female) who participated in the current study. The teachers work in elementary schools. Furthermore, 87 of the teachers work for mentally disabled pupils at special elementary schools. Non-teachers were Ahvaz Jundishapur University of Medical Sciences employees who consider as the control group. They completed the Persian VFI and VTDp questionnaires three times, at the beginning, middle, and end of their office hours for 1 workday.

RESULTS

The current study's findings indicate that the Persian VFI and VTD scores of non-teachers were significantly lower than teachers' scores. Furthermore, teachers of mentally disabled pupils demonstrated higher values from teachers of normal pupils based on the Persian VFI and VTDp scores CONCLUSION: The study results showed that teachers experienced more vocal fatigue and vocal tract discomfort than non-teachers. Furthermore, teachers of mentally disabled pupils indicated more vocal fatigue, the larynx's physical discomfort, and vocal tract discomfort, but this difference was practically small.

Ovine Vocal Fold Tissue Fatigue Response to Accumulated, Large-Amplitude Vibration Exposure at Phonatory Frequencies

Purpose The contribution of tissue mechanical response to vocal fatigue is poorly understood. This study investigated the fatigue response of vocal fold tissues to large-amplitude vibration exposure at phonatory frequencies, using an ex vivo ovine model. Method Twelve sheep vocal fold mucosal specimens were subjected to sinusoidal, simple-shear deformation for prolonged cycles, under a large but physiological shear strain (46%) in a frequency range of 100-230 Hz. The duration of shear varied from a critical vibration exposure limit of 1,040 s to 4 times the limit (4,160 s). Tissue viscoelastic response was quantified by the elastic shear modulus (G'), viscous shear modulus (G″), and damping ratio (G″/G'). Results Distinct response patterns were observed at different frequencies. G' and G″ generally decreased with vibration exposure at 100 Hz, whereas they generally increased with vibration exposure at 200 and 230 Hz. Statistically significant differences were found for G″ increasing with vibration exposure at 200 Hz and damping ratio decreasing with vibration exposure at 200 Hz. Significant increases with frequency were also found for all viscoelastic functions. Results suggested that the contribution of tissue viscoelastic response to vocal fatigue could be highly frequency dependent. In particular, increases in G″ with vibration exposure could lead to high phonation threshold pressures and difficulty sustaining phonation at higher frequencies following prolonged vocalization. Conclusion These preliminary findings may help us better understand vocal fatigue and recovery and should be corroborated by studies with human vocal fold tissues.

The Relationship Between Physiological Mechanisms and the Self-Perception of Vocal Effort

Purpose This study aimed to examine the relationship between a large set of hypothesized physiological measures of vocal effort and self-ratings of vocal effort. Method Twenty-six healthy adults modulated speech rate and vocal effort during repetitions of the utterance /ifi/, followed by self-perceptual ratings of vocal effort on a visual analog scale. Physiological measures included (a) intrinsic laryngeal tension via kinematic stiffness ratios determined from high-speed laryngoscopy, (b) extrinsic suprahyoid and infrahyoid laryngeal tension via normalized percent activations and durations derived from surface electromyography, (c) supraglottal compression via expert visual-perceptual ratings, and (d) subglottal pressure via magnitude of neck surface vibrations from an accelerometer signal. Results Individual statistical models revealed that all of the physiological predictors, except for kinematic stiffness ratios, were significantly predictive of self-ratings of vocal effort. However, a combined regression model analysis yielded only 3 significant predictors: subglottal pressure, mediolateral supraglottal compression, and the normalized percent activation of the suprahyoid muscles (adjusted R 2 = .60). Conclusions Vocal effort manifests as increases in specific laryngeal physiological measures. Further work is needed to examine these measures in combination with other contributing factors, as well as in speakers with dysphonia.

Quantifying Vocal Fatigue Recovery: Dynamic Vocal Recovery Trajectories after a Vocal Loading Exercise

Objectives

We quantified the recovery of voice following a 2-hour vocal loading exercise (oral reading).

Methods

Eighty-six adult participants tracked their voice recovery using short vocal tasks and perceptual ratings after an initial vocal loading exercise and for the following 2 days.

Results

Short-term recovery was apparent, with 90% recovery within 4 to 6 hours and full recovery at 12 to 18 hours. Recovery was shown to be similar to a dermal wound healing trajectory.

Conclusions

The new recovery trajectory highlighted by the vocal loading exercise in the current study is called a vocal recovery trajectory. By comparing vocal fatigue to dermal wound healing, this trajectory is parallel to a chronic wound healing trajectory (as opposed to an acute wound healing trajectory). This parallel suggests that vocal fatigue from the daily use of the voice could be treated as a chronic wound, with the healing and repair mechanisms in a state of constant repair. In addition, there is likely a vocal fatigue threshold at which point the level of tissue damage would shift the chronic healing trajectory to an acute healing trajectory.

The Impact of Cumulative Vocal Demands on Vocal Performance of Student Clinicians in Speech-Language Pathology

Effects of cumulative vocal demands on voice performance of student clinicians majoring in speech-language pathology were observed at three distinct points over the period of an academic semester. Acoustic and aerodynamic voice parameters were monitored in controlled and natural settings; participants also provided subjective information related to their voice usage. Comparisons of voice parameters in student clinicians repeatedly measured throughout an extended period of time did not lead to statistically significant differences. Self-reported data revealed a satisfactory level of knowledge and awareness regarding voice concerns in this population. These outcomes suggested consistent voice stability in this group, over the cycle of an academic semester.

The Measurement and Effects of Vocal Load in Singing Performance. How Much Singing Can a Singer Sing if a Singer Can Sing Songs?

Singing as both an art form and physical activity demands a level of health and skill fitness to meet performance demands. The determination of performance fitness relies on performers' self-evaluations of their vocal capacity for performance, based, amongst other factors, on the current vocal status and ability to manage the associated vocal load. Measurement of load and the impact on the vocal mechanism is complex and influenced by many intrinsic and extrinsic factors. Researchers have attempted to quantify vocal load effects by measuring physical impact stress on the vocal folds, self-reported perceived exertion, and/or clinical evaluation of physiologic, acoustic, or perceptual changes. Most studies have been conducted in laboratory rather than in performance contexts and studies on singers are substantially lacking. Heavy vocal load has been causally associated with the development of voice disorders, although the exact relationship and thresholds for acquiring laryngeal pathology require further elucidation, and little is also known about the development of voice disorders among singers. Further understanding of the short-term and cumulative effect on the vocal folds of performing as a singer and the nature and prevalence of voice problems among singers is crucial to the determination of appropriate prevention and therapeutic management.

Exploring the effect of laryngeal neuromuscular electrical stimulation on voice

Objective:

This study was conducted to explore the potential use of neuromuscular electrical stimulation as an adjunctive treatment for muscle tension dysphonia.

Methods:

Voice data and ratings of fatigue and soreness were obtained for two experiments. Experiment one examined the vocal effects of neuromuscular electrical stimulation applied to the neck for 15 minutes. Experiment two examined the recovery effect of laryngeal neuromuscular electrical stimulation following a vocal loading task among normophonic women.

Results:

No significant differences in vocal function following 15 minutes of laryngeal neuromuscular electrical stimulation were found. Six of 11 participants receiving laryngeal neuromuscular electrical stimulation exhibited improved recovery following the vocal loading task.

Conclusion:

A short session of laryngeal neuromuscular electrical stimulation may be beneficial in reducing muscle fatigue for some individuals. Further investigation is warranted to determine the applicability of laryngeal neuromuscular electrical stimulation in voice therapy.

Effects of speech style, room acoustics, and vocal fatigue on vocal effort

Vocal effort is a physiological measure that accounts for changes in voice production as vocal loading increases. It has been quantified in terms of sound pressure level (SPL). This study investigates how vocal effort is affected by speaking style, room acoustics, and short-term vocal fatigue. Twenty subjects were recorded while reading a text at normal and loud volumes in anechoic, semi-reverberant, and reverberant rooms in the presence of classroom babble noise. The acoustics in each environment were modified by creating a strong first reflection in the talker position. After each task, the subjects answered questions addressing their perception of the vocal effort, comfort, control, and clarity of their own voice. Variation in SPL for each subject was measured per task. It was found that SPL and self-reported effort increased in the loud style and decreased when the reflective panels were present and when reverberation time increased. Self-reported comfort and control decreased in the loud style, while self-reported clarity increased when panels were present. The lowest magnitude of vocal fatigue was experienced in the semi-reverberant room. The results indicate that early reflections may be used to reduce vocal effort without modifying reverberation time.

The Effect of Head Position and/or Stance on the Self-perception of Phonatory Effort

BACKGROUND

Vocal fatigue is a common but poorly defined complaint of patients presenting with voice disorders. Definitions of vocal fatigue generally include increased self-perceived phonatory effort resulting from references to vocal loading or prolonged voice use resulting in deterioration of function. The present study looks at the role of posture, specifically head position and stance, in self-perceived phonatory effort.

METHODS

Forty-six healthy adults, 13 males and 33 females (mean age was 27.5), with no history of vocal problems/disorders within the past year were recruited. Subjects were asked to sustain the vowel /a/ at a comfortable pitch and loudness for 5-10 seconds in each of six positions: sitting and standing in the manner habitual for each subject, two exaggerated positions of the head (head back and head forward), and two exaggerated positions in standing (standing with knees locked and with knees soft). Each position was repeated three times in randomized order, resulting in 18 trials for each subject. After each repetition of the sustained /a/, subjects were asked to rate their experience of vocal effort using a 100-mm visual analog scale (0-40 least effort, 40-60 habitual effort, and 60-100 increased effort).

RESULTS

Repeated measures analysis of variance revealed significant difference in the self-perceived phonatory effort levels across positions (P value < 0.001). The exaggerated forward and back head positions in both sitting and standing positions showed the greatest significance on the Tukey post hoc tests (P < 0.000).

CONCLUSIONS

Based on the findings, posture may play a more important role in vocal fatigue than previously thought.

Measuring vocal function in professional music theater singers: construct validation of the Evaluation of the Ability to Sing Easily (EASE)

OVERVIEW

Working music theater singers (MTS) typically have a heavy vocal load and little is known about their perception of vocal function. The Evaluation of the Ability to Sing Easily (EASE) was used to assess professional MTS' perceptions of current singing voice status and to compare scores across demographic and performance characteristics and to evaluate the construct validity of the EASE and its subscales (VF = Vocal Fatigue, PRI = Pathologic-Risk Indicators).

METHODS

Professional MTS (n = 284) completed an online survey including the EASE and two additional Vocal Concern (VC) items. Scores were compared across age, gender, whether currently working, role, perceived vocal load over the past 24 h and self-reported voice problem.

RESULTS

For the whole cohort, statistically significant differences were found on all subscales according to whether or not singers perceived themselves to have a voice problem (p < 0.001). Currently performing singers were significantly different from those not performing in a show on the EASE Total (p = 0.014) and VF (p = 0.002), but not for PRI and VC. In the currently performing singer group, significant differences were found for gender, role and perceived voice problem on the EASE Total and all subscales (p < 0.01). Significantly higher VF scores were recorded for singers with heavy vocal load (p = 0.01), but there were no differences on the EASE Total (p = 0.57), PRI (p = 0.19) or VC subscales (p = 0.53). Among these performing singers, no significant age differences were found for any EASE subscales.

CONCLUSIONS

These findings provide further validation of the EASE as a useful tool for measuring singers' perceptions of vocal function and suggest that the subscales should be scored separately. Future evaluation of the EASE against objective clinical assessments (e.g., videostroboscopy) is recommended.

Voice use in professional soccer management

Vocal load related to heavy voice use in particular professions increases the risk of occupational voice disorders. Research on professional voice use has primarily focused on educators, singers, and call-centre advisors. This paper describes the daily experiences of professional soccer managers' occupational voice use through qualitative methods. Four global themes were identified: 1) voice uses, 2) factors affecting voice change, 3) impact of voice use, and 4) the importance of voice in soccer management. All describe the nature of soccer managers' vocal demands. Risk factors for voice disorders include intense and prolonged voice use in environments with adverse acoustic properties for speakers and poor phonation methods. Research on vocal behaviours and early prevention programmes for this population group is warranted.

A comparison of vocal demands with vocal performance among classroom student teachers

PURPOSE

This investigation compared voice performance of student teachers across an academic semester in order to examine the effect of increasing demands on their voice.

METHOD

A repeated measures design was applied to the data analysis: all participants were tested three separate times throughout the semester. The equipments used for monitoring vocal behavior were the Ambulatory Phonation Monitor (APM), the Computerized Speech Lab (CSL), and the Phonatory Aerodynamic System (PAS), which are computer-based systems for acoustic and aerodynamic assessment of voice. Additionally, participants completed surveys related to voice usage.

RESULTS

In this study, most voice parameters of student teachers measured in a natural setting and in a controlled environment indicated changes that revealed progressive instability and noise in the course of an academic semester. Additional comparisons demonstrated differences between voice usage in the school environment and voice produced in the voice lab. Self-reported information demonstrated overall reduced awareness regarding preventive methods for voice disorders.

CONCLUSIONS

Based on the results of this study, increased teaching-related voice demands associated with reduced awareness of voice production and preventive measures of voice disorders may have a detrimental impact on voice performance, leading to a risk of developing voice disorders.

LEARNING OUTCOMES

Participants will recognize the importance of clarifying and quantifying the relationship of vocal demands and voice performance among student teachers.

The inability to produce soft voice (IPSV): a tool to detect vocal change in school-teachers

PURPOSE

This study investigated whether clinicians could detect voice changes reported by teachers, from self-ratings teachers conducted of their inability to produce soft voice (IPSV).

METHODS

Ten teachers wore a vocal dosimeter and completed daily IPSV ratings approximately every 2 hours for 14 days. Following the 2 weeks of dosimetry, two speech clinicians specialized in voice rated the teachers' IPSV from dosimeter recordings. Teacher and clinician ratings were compared for each participant.

RESULTS

Although agreement between teacher and clinician ratings was not significant, descriptive analyses demonstrated an average difference score of 1.7 (SD 1.4) between teacher and clinician ratings.

CONCLUSIONS

This study supports the potential usefulness of the IPSV as a simple tool to detect voice changes in oneself or others.

From Reactive Intervention to Proactive Prevention: The Evolution of Occupational Dysphonia

Voice clinicians long have been aware of the concept of professional voice users: individuals who work in professions that have a higher incidence and increased risk for voice disorders. This realization, coupled with the documented impact of work-related dysphonia on the economy, has resulted in a growing international interest in developing occupational health benchmarks for voice use, similar to other standards developed for work-related factors such as noise-induced hearing loss. In this article, we review current perspectives and examine some issues related to occupational vocal health.

[Voice analysis before and after vocal tiredness]

BACKGROUND/AIM

A school teacher's occupation is one of the most vocal demanding professions. Vocal tiredness affects acoustic characteristics of voice, leads to the change in acoustic quality during vocal production. The aim of this study was to examine the influence of vocal tiredness on voice acoustic characteristics of school teachers.

METHODS

The study included 36 school teachers (16 male and 20 female) of 27-58 years of age. Vocal tiredness was evaluated by analyzing acoustic parameters of voice, using computerized laboratory "Kay Elemetrics". The voices were recorded before the first class on the beginning of a working week and after the last class at the end of a working week. Signal, noise and tremor parameters were processed. In their analysis the methods of descriptive statistics, as well as the analytical statistics (Student's t-test for paired samples, chi2 test, Mann Whitney U-test and Pearson's correlation coefficient) were applied.

RESULTS

The obtained results showed statistically significant differences in average values of parameters as a consequence of the vocal tiredness (p < 0.01), while gender, age and being smoker or not, did not have a significant effect on voice acoustic characteristics in this group of examinees (p > 0.05).

CONCLUSION

The results of the study suggest a casual relationship between vocal tiredness and voice quality in vocal professionals.

Voice problems experienced by Finnish comprehensive school teachers and realization of occupational health care

A survey was conducted among teachers to explore 1) risk factors of voice disorders, 2) the number and nature of problems experienced, 3) the need for medical help, and 4) how occupational health care reacts to this need. Additionally, the knowledgeability of occupational health care physicians and the way treatment of voice disorders is currently organized was explored. Of the 181 teachers who responded, 42% reported voice symptoms occurring daily or weekly. Every tenth teacher also had vocal nodules, and 40% of those with recurring voice problems had been on sick-leave. The respondents suggested improvements in occupational health care: it should also cover prevention, waiting times need to be shortened and care chains established, and resources need to be allocated for voice therapy services.

Loud voice during environmental noise exposure in patients with vocal nodules

The aim was to investigate how female patients with vocal nodules use their voices when trying to make themselves heard over background noise. Ten patients with bilateral vocal fold nodules and 23 female controls were recorded reading a text in four conditions, one without noise and three with noise from cafés/pubs, played over loudspeakers at 69, 77 and 85 dBA. The noise was separated from the voice signal using a high-resolution channel estimation technique. Both patients and controls increased voice sound pressure level (SPL), fundamental frequency (F0), subglottal pressure (Ps) and their subjective ratings of strain significantly as a main effect of the increased background noise. The patients used significantly higher Ps in all four conditions. Despite this they did not differ significantly from the controls in voice SPL, F0 or perceived strain. It was concluded that speaking in background noise is a risk factor for vocal loading. Vocal loading tests in clinical settings are important and further development of assessment methods is needed.

Voice symptoms of call-centre customer service advisers experienced during a work-day and effects of a short vocal training course

Occupational voice users often suffer from voice symptoms to varying extents. The first goal of this study was to find out how telephone customer service advisers experience voice symptoms at different moments of the working day. The second goal was to investigate the effects of a short vocal training course arranged for telephone workers. The results indicate that although the subjects did not suffer from severe voice problems, the short vocal training course significantly reduced some of the vocal symptoms they had experienced. The results suggest that systematic consultation and training for occupational voice users in the field of occupational voice care would be advantageous.

Loud Speech in Realistic Environmental Noise: Phonetogram Data, Perceptual Voice Quality, Subjective Ratings, and Gender Differences in Healthy Speakers

A new method for cancelling background noise from running speech was used to study voice production during realistic environmental noise exposure. Normal subjects, 12 women and 11 men, read a text in five conditions: quiet, soft continuous noise (75 dBA to 70 dBA), day-care babble (74 dBA), disco (87 dBA), and loud continuous noise (78 dBA to 85 dBA). The noise was presented over loudspeakers and then removed from the recordings in an off-line processing operation. The voice signals were analyzed acoustically with an automatic phonetograph and perceptually by four expert listeners. Subjective data were collected after each vocal loading task. The perceptual parameters press, instability, and roughness increased significantly as an effect of speaking loudly over noise, whereas vocal fry decreased. Having to make oneself heard over noise resulted in higher SPL and F0, as expected, and in higher phonation time. The total reading time was slightly longer in continuous noise than in intermittent noise. The women had 4 dB lower voice SPL overall and increased their phonation time more in noise than did the men. Subjectively, women reported less success making themselves heard and higher effort. The results support the contention that female voices are more vulnerable to vocal loading in background noise.

Methods to study pre-school teachers' voice at work: simultaneous recordings with a voice accumulator and a DAT recorder

Long-term recordings with reliable methods are desirable for objective documentation of voice use during natural conditions. The purpose of this study was to evaluate a voice accumulator (VAC) with a digital audiotape (DAT) recorder as a reference. The VAC is based on a microprocessor that accumulates information about fundamental frequency (F0) and phonation time. A contact microphone attached to the front of the neck registers vocal fold vibrations. The DAT recorder was connected to two microphones for airborne signals placed at equal distance from the mouth close to the subject's ears. The computer program Aura was used to separate the subject's voice from the background noise. The Soundswell program was used for F0 and phonation time analysis. Two tests were performed: 1) One female speech-language pathologist was recorded with the two devices simultaneously in a sound-proof booth. She read a standard text with different voice qualities and sustained vowels with increasing F0 and intensity separately. The results showed good agreement between the two methods with respect to F0 and phonation time. However, the VAC failed to register high frequencies above around 440 Hz as well as low intensities. 2) Three female pre-school teachers were recorded with the two devices simultaneously during a working day. Results showed high correlations between the two methods in terms of long-term measurements of F0 and phonation time for two subjects For one subject with subcutaneous soft tissue on the neck, the registration with the contact microphone was not reliable. It was concluded that the VAC has potential for assessment of occupational voice disorders if certain limitations of the method are considered.

Vocal behavior and vocal loading factors for preschool teachers at work studied with binaural DAT recordings

Preschool teachers are at risk for developing voice problems such as vocal fatigue and vocal nodules. The purpose of this report was to study preschool teachers' voice use during work. Ten healthy female preschool teachers working at daycare centers (DCC) served as subjects. A binaural recording technique was used. Two microphones were placed on both sides of the subject's head, at equal distance from the mouth, and a portable DAT recorder was attached to the subject's waist. Recordings were made of a standard reading passage before work (baseline) and of spontaneous speech during work. The recording technique allowed separate analyses of the level of the background noise, and of the subjects' voice sound pressure level, mean fundamental frequency, and total phonation time. Among the results, mean background noise level for the ten DCCs was 76.1 dBA (range 73.0-78.2), which is more than 20 dB higher than what is recommended where speech communication is important (50-55 dBA). The subjects spoke on an average of 9.1 dB louder (p < 0.0001), and with higher mean fundamental frequency (247 Hz) during work as compared to the baseline (202 Hz) (p < 0.0001). Mean phonation time for the group was 17%, which was considered high. It was concluded that preschool teachers do have a highly vocally demanding profession. Important steps to reduce the vocal loading for this occupation would be to decrease the background noise levels and include pauses so that preschool teachers can rest their voices.