Eeva Sala

The prevalence of voice disorders among day care center teachers compared with nurses: a questionnaire and clinical study.

The acceptance of voice disorders by day care center teachers as an occupational disease is not an invariably established practice. This is due to the lack of reliable evidence of a higher risk for voice disorders in this profession. To find out the risk of voice disorders, an epidemiological study was conducted among day care center teachers (n = 262), using hospital nurses (n = 108) as a control group. Symptoms were charted by a questionnaire. In a clinical examination made by a laryngologist, the voice quality was assessed and the laryngeal status noted. Teachers at day care centers had significantly more voice disorders than did nurses. Vocal nodules and laryngitis findings appeared significantly more frequently among day care center teachers than among those in the control group. The results prove voice disorders to be more frequent among day care center teachers than among control group subjects, and also that the main cause for this may be a higher vocal loading among day care center teachers than among control group subjects.

Prevalence of voice disorders among future teachers.

An epidemiological study was conducted in order to find out the prevalence of voice disorders among students studying to be teachers. Vocal symptoms were inquired of 226 students. Their voices were assessed perceptually by a speech therapist and those who had abnormal voice quality or reported several vocal symptoms were referred to a clinical examination by a laryngologist. The results showed that 20% of this population reported two or more vocal symptoms during the previous year and that 19% had an organic voice disorder. This reinforces the need for clinical evaluation of students with vocal symptoms and more vocal training in the teacher education programs.

Objective Analysis of Vocal Warm-Up with Special Reference to Ergonomic Factors

Vocal warm-up was studied in terms of changes in voice parameters during a 45-minute vocal loading session in the morning. The voices of a randomly chosen group of 40 female and 40 male young students were loaded by having them read a novel aloud. The exposure groups (5 females and 5 males per cell) consisted of eight combinations of the following factors: (1) low (25 +/- 5%) or high (65 +/- 5%) relative humidity of ambient air; (2) low [< 65 dB(SPL)] or high [> 65 dB(SPL)] speech output level during vocal loading; (3) sitting or standing posture during vocal loading. Two sets of voice samples were recorded: a resting sample before the loading session and a loading sample after the loading session. The material recorded consisted of /pa:ppa/ words produced normally, as softly and as loudly as possible in this order by all subjects. The long /a/ vowel of the test word was inverse-filtered to obtain the glottal flow waveform. Time domain parameters of the glottal flow [open quotient (OQ), closing quotient (CQ), speed quotient (SQ), fundamental frequency (F0)], amplitude domain parameters of the glottal flow [glottal flow (fAC) and its logarithm, minimum of the first derivative of the glottal flow (dpeak) and its logarithm, amplitude quotient (AQ), and a new parameter, CQAQ], intraoral pressure (p), and sound pressure level (SPL) values of the phonations were analyzed. Voice range profiles (VRP) and the singers formant (g/G, a/A, cl/c, e1/e, g1/g for females/males) of the loud phonation were also measured. Statistically significant differences between the preloading and postloading samples could be seen in many parameters, but the differences depended on gender and the type of phonation. In females the values of CQ, AQ, and CQAQ decreased and the values of SQ and p increased in normal phonations; the values of fAC, dpeak, and SPL increased in soft phonations; the values of AQ and CQAQ decreased in loud phonations; the harmonic energy in the singers formant region increased significantly at every pitch. In males the values of OQ and AQ decreased and the values of dpeak, F0, p, and SPL increased in normal phonations; the values of fAC and p increased in soft phonations. The changes could be interpreted as signs of a shift toward hyperfunctional voice production. Low humidity was associated with more hyperfunctional changes than high humidity. High output was associated with more hyperfunctional changes than low output. Sitting position was associated with an increasing trend at both margins of male VRP, whereas the case was the opposite for standing position.

Loading-related subjective symptoms during a vocal loading test with special reference to gender and some ergonomic factors.

Vocal loading-related subjective symptoms were studied in a day-long vocal loading test. The voices of 40 female and 40 male voluntary young students were loaded by having them read aloud a novel for five times 45 min. The subjective symptoms that occurred during the vocal loading session were reported by filling in a questionnaire after each session. The responses loaded on five factors in a factor analysis: (1) ‘central fatigue’; (2) ‘symptoms of the neck, shoulders and back’; (3) ‘drying in the mouth and throat’; (4) ‘symptoms of the throat’; (5) ‘symptoms of the voice’. The exposure groups (5 females and 5 males per cell) consisted of eight combinations of the following factors: (1) low (25 ± 5%) or high (65 ± 5%) relative humidity of ambient air; (2) low [<65 dB(SPL)] or high [>65 dB(SPL)] speech output level of vocal loading; (3) sitting or standing posture during vocal loading. The lowest mean score for symptoms pooled over the test were found in ‘symptoms of the neck, shoulders and back’ and the highest mean symptom score in ‘drying in the mouth and throat’ and ‘symptoms of the throat’. Most symptoms were at their minimum during the first loading session and increased statistically significantly to a peak mean value after three or five vocal loading sessions. Statistically significant differences in the mean level between the gender or exposure groups emerged for ‘central fatigue’ (humidity had clear effects) and ‘symptoms of the neck, shoulders and back’ (gender, humidity and posture had clear effects). In these cases, females had more symptoms than males; the low-humidity group had more symptoms than the high-humidity group, and the standing subjects had more symptoms than the sitting subjects.

A fast and easy screening method for voice disorders among teacher students

A recent study concerning voice disorders among future teachers showed that about 20% of the students had a voice disorder. Most of the disorders were organic. In the current study, we describe a voice-screening method that can be administered by the health care personnel in order to select students for further examination by the speech language therapist and/or phoniatrician. The screening method consists of a perceptual assessment of voice quality and a questionnaire concerning vocal symptoms. As criterion for further medical investigation and voice therapy, we selected a score of 35 mm or above on a visual analogue scale assessing Grade, i.e. overall grade of hoarseness and/or two or more weekly or more often occurring vocal symptoms. The results showed that health care personnel with some training in assessing voices using the questionnaire are competent to perform a rough voice screening on students.

A method to measure speaking time and speech sound pressure level.

Many voice disorders are associated with vocal loading, but easy measurement of the vocal load has not been possible so far. To fulfil this need, an easily accessible method was developed and tested. Speaking time and speaking sound level can be recorded during normal work, and measurement can be made in a noisy environment. The measurement is made with a pair of modern noise exposure analysers from which the data is transferred to a personal computer, and the voice speaking time and the related sound pressure levels are calculated with a spreadsheet program. Suitable meters are available from various manufacturers. The method may be applied to measure the need of voice use in different professions, assessing a person’s performance in his or her work or evaluating the effects of voice therapy on speaking performance.

The Effects of Post-Loading Rest on Acoustic Parameters with Special Reference to Gender and Ergonomic Factors

It is a common experience that vocal quality changes during a break in vocal loading. The purpose of the present study was (1) to analyse the effects of a short post-loading vocal rest in terms of changes in a large variety of voice parameters and (2) to assess the possible effects of gender and exposure factors on these changes. The voices of a randomly chosen group of 40 female and 40 male young students were loaded by having them read aloud a novel. Two sets of voice samples were recorded: a post-loading sample after three times 45-min vocal loading during the morning and a post-resting sample after a 45-min lunch break. The material recorded consisted of /pa:ppa/ words produced normally, as softly and as loudly as possible in this order. The long /a/ vowel of the test word was inverse-filtered to obtain the glottal flow waveform. Time-domain parameters of the glottal flow [open quotient, closing quotient (ClQ), speed quotient (SQ), fundamental frequency (F₀)], amplitude-domain parameters of the glottal flow [glottal flow, minimum of the first derivative of glottal flow, amplitude quotient (AQ)], intraoral pressure and sound pressure level (SPL) values of the phonations were analysed. Voice range profiles and the singer’s formant (g/G, a/A, c∣/c, e∣/e, g∣/g for females/males) of the loud phonations were also measured. The subjects were divided into eight exposure groups (5 females and 5 males per cell) according to different combinations of the following exposure factors: (1) low (25 ± 5%) or high (65 ± 5%) relative humidity of ambient air, (2) low [<65 dB(A)] or high [>65 dB(A)] speech output level during vocal loading and (3) sitting or standing posture during vocal loading. Statistically significant differences between the post-loading and post-resting samples could be observed in many parameters (the values of intraoral pressure in the soft phonations decreased, the values of SPL and SQ in the normal phonations decreased and the values of AQ, F₀ and ClQ in the normal phonations increased). Most of the differences reflected a shift towards softer phonation. Gender and exposure factors also had significant effects.

Connections between Voice Ergonomic Risk Factors in Classrooms and Teachers’ Voice Production

Objective: The aim of the study was to investigate if voice ergonomic risk factors in classrooms correlated with acoustic parameters of teachers’ voice production. Methods: The voice ergonomic risk factors in the fields of working culture, working postures and indoor air quality were assessed in 40 classrooms using the Voice Ergonomic Assessment in Work Environment – Handbook and Checklist. Teachers (32 females, 8 males) from the above-mentioned classrooms recorded text readings before and after a working day. Fundamental frequency, sound pressure level (SPL) and the slope of the spectrum (alpha ratio) were analyzed. Results: The higher the number of the risk factors in the classrooms, the higher SPL the teachers used and the more strained the males’ voices (increased alpha ratio) were. The SPL was already higher before the working day in the teachers with higher risk than in those with lower risk. Conclusion: In the working environment with many voice ergonomic risk factors, speakers increase voice loudness and use more strained voice quality (males). A practical implication of the results is that voice ergonomic assessments are needed in schools.

Teachers’ Working Postures and Their Effects on the Voice

Objective: To evaluate associations between voice and working postures used during teaching. Methods: A researcher assessed 30 teachers’ typical working postures of the torso, head, shoulders, upper back, and arms by observing and/or asking questions about them. Teachers’ options to rest and to adjust furniture according to their needs were also elicited. Voice symptoms were evaluated through 2 self-assessment forms. Fundamental frequency, sound pressure level (SPL), and alpha ratio were calculated from voice samples recorded before, during, and after teaching. Results: The head was most typically in an unergonomic posture while speaking (in 60% of participants). Other frequently used unergonomic postures were hunched upper back (55%), raised shoulders (46%), and twisted torso (43%). Head and torso twisted and arms upheld were associated with specific voice symptoms and head postures and hunched upper back with voice use. The number of postures was also connected with voice use: if the teachers used over 3 unergonomic postures, their SPL was higher and the voice broke more often than in those with a lower number of postures. Conclusion: Unergonomic postures during speaking affect the voice. It is important to evaluate working postures as part of voice ergonomic assessment in voice patients.