Vocal loading among day care center teachers

Outcome of Resonant Voice Therapy for Female Teachers With Voice Disorders: Perceptual, Physiological, Acoustic, Aerodynamic, and Functional Measurements

Teachers have a high percentage of voice problems. For voice disordered teachers, resonant voice therapy is hypothesized to reduce voice problems. No research has been done on the physiological, acoustic, and aerodynamic effects of resonant voice therapy for school teachers. The purpose of this study is to investigate resonant voice therapy outcome from perceptual, physiological, acoustic, aerodynamic, and functional aspects for female teachers with voice disorders. A prospective study was designed for this research. The research subjects were 24 female teachers in Taipei. All subjects received resonant voice therapy in groups of 4 subjects, 90 minutes per session, and 1 session per week for 8 weeks. The outcome of resonant voice therapy was assessed from auditory perceptual judgment, videostroboscopic examination, acoustic measurements, aerodynamic measurements, and functional measurements before and after therapy. After therapy the severity of roughness, strain, monotone, resonance, hard attack, and glottal fry in auditory perceptual judgments, the severity of vocal fold pathology, mucosal wave, amplitude, and vocal fold closure in videostroboscopic examinations, phonation threshold pressure, and the score of physical scale in the Voice Handicap Index were significantly reduced. The speaking Fo, maximum range of speaking Fo, and maximum range of speaking intensity were significantly increased after therapy. No significant change was found in perturbation and breathiness measurements after therapy. Resonant voice therapy is effective for school teachers and is suggested as one of the therapy approaches in clinics for this population.

Voicing and silence periods in daily and weekly vocalizations of teachers

The National Center for Voice and Speech (NCVS) data bank on voice dosimetry was used to study the distributions of continuous voicing periods and silence periods in 31 teachers over the duration of two weeks. Recordings were made during all awake hours of the day. Voicing periods were grouped into half decades, ranging from 0.0316 to 0.10 s for the shortest periods of phonation to 31.6-100 s for the longest periods of phonation. Silence periods were grouped into similar half decades, but ranged up to periods of several hours. On average, the teachers had 1800 occurrences of voicing (onset followed by offset) per hour at work and 1200 occurrences per hour while not at work. Voicing occurred 23% of the total time at work, dropping to 13% during off-work hours and 12% on weekends. The greatest accumulation of voicing occurred in the 0.316-1.0 s voicing periods, whereas the greatest accumulation of silence occurred in the 3-10 s silence periods. The study begins to lay the groundwork for understanding vocal fatigue in terms of repetitive motion and collision of tissue, as well as recovery from such mechanical stress.

Objective measurement of vocal fatigue in classical singers: a vocal dosimetry pilot study

OBJECTIVES

To collect objective vibration dose data on singers and relate them to subjective measurements of vocal fatigue.

STUDY DESIGN AND SETTING

Seven subjects completed a 2-week study period. The National Center for Voice and Speech (NCVS) dosimeter recorded vocal load, soft phonation tasks, and subjective soft voice ratings. Three vocal doses (time, distance, and cycle) were measured in classical singers' larynges during an intensive practice period.

RESULTS

Spikes in vocal load are reflected as harsher subjective ratings on the same day as well as 24-72 hours later. When at least 48 hours of vocal rest occurred before a vocal load, improved subjective evaluations were seen after the load.

CONCLUSIONS

The NCVS dosimeter appears to be an effective tool for data collection on prolonged use of the voice.

SIGNIFICANCE

This is the first multi-day study comparing objective and subjective data on vocal fatigue in a group of professional singers.

Estimation of sound pressure levels of voiced speech from skin vibration of the neck

How accurately can sound pressure levels (SPLs) of speech be estimated from skin vibration of the neck? Measurements using a small accelerometer were carried out in 27 subjects (10 males and 17 females) who read Rainbow and Marvin Williams passages in soft, comfortable, and loud voice, while skin acceleration levels (SALs) and SPLs were simultaneously registered and analyzed every 30 ms. The results indicate that the mean SPL of voiced speech can be estimated with accuracy better than +/-2.8 dB in 95% of the cases when the subjects are individually calibrated. This makes the accelerometer an interesting sensor for SPL measurement of speech when microphones are problematic to use (e.g., noisy environments or in voice dosimetry). The estimates of equivalent SPL, which is the logarithm of averaged relative energy of voiced speech, were found to be up to 1.5 dB less accurate than the mean SPL. The estimation accuracy for instantaneous SPLs was worse than for the mean and equivalent SPLs (on average +/-6 and +/-5 dB for males and females, respectively).

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.

Changes in the Prevalence of Vocal Symptoms Among Teachers During a Twelve-Year Period

Vocal symptoms and voice disorders among teachers were studied in 1988 using a questionnaire designed to obtain information on six vocal symptoms that had appeared during the past 2 years. Twelve percent of the 478 respondents reported vocal symptoms occurring weekly or more often. The study was repeated using the same questionnaire in 2001. The results of this second study (n=241) indicate that vocal symptoms had increased considerably. Twenty-nine percent of the teachers reported symptoms occurring weekly or more often, and 20% reported two symptoms or more occurring at least once a week, which is significantly more than in 1988. Accordingly, voice disorders are probably a growing problem among teachers. Several factors may explain these increases. In 2001, the teachers complained more often about increases in the size of their classes. Factors that disturbed normal work routines, such as noisy or misbehaving pupils, had also increased significantly. A growing number of misbehaving pupils probably cause increased background noise and stress and, thus, increase the vocal symptoms in teachers.

Long-term exposure to noise impairs cortical sound processing and attention control

Long-term exposure to noise impairs human health, causing pathological changes in the inner ear as well as other anatomical and physiological deficits. Numerous individuals are daily exposed to excessive noise. However, there is a lack of systematic research on the effects of noise on cortical function. Here we report data showing that long-term exposure to noise has a persistent effect on central auditory processing and leads to concurrent behavioral deficits. We found that speech-sound discrimination was impaired in noise-exposed individuals, as indicated by behavioral responses and the mismatch negativity brain response. Furthermore, irrelevant sounds increased the distractibility of the noise-exposed subjects, which was shown by increased interference in task performance and aberrant brain responses. These results demonstrate that long-term exposure to noise has long-lasting detrimental effects on central auditory processing and attention control.

Occupational Safety and Health Aspects of Voice and Speech Professions

A well-functioning voice is an essential tool for one third of the labour force. Vocal demands vary to a great extent between the different voice and speech professions. In professions with heavy vocal loading (e.g. school and kindergarten teachers), occupational voice disorders threatening working ability are common. Vocal loading is a combination of prolonged voice use and additional loading factors (e.g. background noise, acoustics, air quality) affecting the fundamental frequency, type and loudness of phonation or the vibratory characteristics of the vocal folds as well as the external frame of the larynx. The prevention and treatment of occupational voice disorders calls for improved occupational safety and health (OSH) arrangements for voice and speech professionals. On the basis of epidemiological and acoustic-physiological research, the presence of risk to vocal health can be substantiated. From the point of view of the physical load on the vocal apparatus, loading-related physiological changes (adaptation) may play a role in the occupational risk. Environmental factors affect vocal loading changes. In teaching professions, the working environment is shared with children, who benefit from amendments of OSH legislation concerning their teachers.