Protective and Risk Factors Associated With Voice Strain Among Teachers in Castile and Leon, Spain: Recommendations for Voice Training
n de los Tratamientos Factores de Riesgo y Proteccio
tricos en Docentes de Castilla y Leo
n: Pautas Fonia
n Vocal para la Formacio ~ ez, and †Ioseba Iraurgi, *Burgos and yBilbao, Spain *Silvia Ubillos, *Javier Centeno, *Jaime Iban Summary: Objectives. The aim of this research was to know the protective and risk factors associated with voice strain in teachers. Method and Study Design. A total of 675 teachers from Castille and Le
on, Spain took part in the research within an age range between 23 and 66 years (from nursery school to university). A cross-sectional, descriptive, and analytic design was applied to data from a self-administered questionnaire. Results. The research showed that 16.4% had suffered some voice disorder and a remarkable percentage had never received any kind of voice training. The bivariate and multivariate analyses show that the size of the classroom, being a primary school teacher, teaching physical education, the noise caused by the students in the classroom, the struggle to keep the order within the class, raising the voice, and bad sleep are risk factors in the voice disorders. Each learning stage features a different risk factor, namely in nursery school, the noise caused by the pupils; in primary education, raising the voice; and in secondary education, the struggle to keep the order within the class. All these risk factors are linked with each other. Conclusions. The preventive measures must provide adequate answers to the voice requirements for every subject and stage, and these preventive measures must be based on the educational psychology principles to help the teachers deal with the problems originated by the lack of authority or the noise made by the students, using the proper voice techniques. Key Words: Phoniatric pathology–Teachers–Protective and risk factors–Voice training. INTRODUCTION Several researchers confirmed years ago that there is an intrinsic relationship between voice-related problems and teaching.1–5 Nevertheless, despite the scientific evidence, the voice-related disorders in the teaching profession appear, in Spain, in a recent list of occupational illnesses, although they did not enter into force until January 1, 2007.6 Different studies2,7–14 have noted the high prevalence of voice disorders among professional teachers, fluctuating between 17% and 63%, reaching an high of 80%. The review performed by Garcia et al14 confirmed the high prevalence of voice disorders in teachers, for whom it is two- to three-fold more frequent than for the general population. As other authors15,16 have indicated, the prevalence of voice disorders among teachers varies significantly owing to the different sampling procedures, the different operationality of the voice problem variable, the methodological strategies used to detect the presence of a phoniatric disorder, the different ways of recording these disorders, and the increase in voice disorders over recent years.

Accepted for publication August 11, 2014. From the *University of Burgos, c/ Villadiego s/n, Burgos, Spain; and the yUniversity of Deusto, Avenida de las Universidades, Bilbao, Spain. Address correspondence and reprint requests to Silvia Ubillos, University of Burgos, c/ Villadiego s/n, 09001 Burgos, Spain. E-mail: [email protected] Journal of Voice, Vol. 29, No. 2, pp. 261.e1-261.e12 0892-1997/$36.00 Ó 2015 Published by Elsevier Inc. on behalf of The Voice Foundation http://dx.doi.org/10.1016/j.jvoice.2014.08.005

In response to this situation, it was necessary to know what the protective and the risk factors were in the face of possible voice problems. All of these were with a view to developing programs with the objective of endowing students and professional teachers with a larger amount of positive and healthy resources and practices, both in the field of work and in their personal life. Aspects related to voice pathologies were divided into different factors to give the investigation clear boundaries, namely sociodemographic characteristics, working conditions, class management techniques, voice training, and certain healthy habits. Among various sociodemographic characteristics, most studies2,10,17–23 have shown that the prevalence of phoniatric disorders is higher in women than in men. Some authors18,24 explain that women have a smaller larynx and the vibration frequencies of their vocal folds are higher than men, which itself is a cause of more voice disorders. With regard to working conditions, the educational level at which teachers exercise their profession, their years as a teacher, the subject matter they teach, the number of weekly teaching hours, and the number of students in the class have all been studied. Studies have found that, in general, nursery, primary, and secondary school teachers are those presenting the highest rate of voice pathologies, whereas the prevalence of this type of disorder among university teachers is less frequent.15,22,25,26 Among

261.e2 the possible causes, Ga~ net et al10 argue that voice strain in the university setting is less prevalent owing to the reduced number of classroom hours and the age of the students. It is generally accepted that vocal performance decreases with age, especially among voice strained professions, which may lead to occupational dysphonia throughout the teaching years. However, two studies27 pointed out that there is no unanimity over the years of teaching experience. Some researchers4,10,28 found that the longer the length of service, the greater the prevalence of teachers with the symptoms of voice-related disorders, although length of service might also be a protective factor, as classroom practice could always improve with experience. Accordingly, Kooijman et al29 confirmed a decrease of voice complaints during the career of the teachers. On the other hand, authors such as Chen et al,30 Preciado et al,11 or Tavares and Martins31 stated that the age and years spent teaching had no cumulative effect on voice disorders among teaching staff. If we look at teaching load, a great number of researchers26,31– 33 noted that dysphonic patients had more classroom hours a week than nondysphonic patients. Nevertheless, there is no agreement on this variable. In other studies,10,28,34 teaching load was not associated with phoniatric pathologies. The referenced literature underlines that the appearance of dysphonias is strongly associated with the teaching of certain subjects, such as foreign languages, language and literature, mathematics, music, and physical education.4,16,22 According to Preciado,26 the increase of voice disorders among teachers of language and literature and foreign languages is owing to the predominance of oral over written work in the classroom. Mathematics teachers put a lot of information on the blackboard and (in the absence of interactive whiteboards) inhale a lot of chalk dust, which deposits itself on the laryngeal mucous complicating the lubrication of the larynx and exacerbating symptoms of irritation, coughing, and ‘‘rasping,’’ thereby increasing phonatory voice disorders. With regard to music teachers, they are more likely to suffer frequent voice disorders because of inappropriate changes from song to the spoken word. Cantor Cutiva et al27 noted that several publications consistently observed that physical education teachers reported voice disorders more often than teachers of other subjects. A possible explanation is that those teachers are forced to work in open or very roomy places with poor acoustics as well as talking, while demonstrating the exercises, being both damaging factors for the voice. The number of students in the classroom has been marked by several authors as a risk factor for voice problems.14,23,26,29,31 The study performed by Preciado26 stated that at the level of nursery education and the first years of primary education, dysphonic teachers had a higher number of students than nondysphonic teachers. Urrutikoetxea et al13 considered that having a lower number of students in class might suppose less voice exertion. The way teachers perceive noise generated by students in the classroom and their capability to maintain order in the classroom, as well as the phonatory techniques they used to capture the attention of students also appear to play an important role in voice problems.

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It is understood that one among other factors that contributes to the development of dysphonia among teachers is a noisy environment.1,14,22,23,27,33,35–40 Adverse acoustic conditions in school rooms (inappropriate materials of walls, ceilings and floors that propagate noise and reverberations, not using voice amplification to decrease phonotory overload, and so on.) and the students themselves, either because of their age or because of their behavior, may all be the sources of noise. On numerous occasions, the noisy environment is so strong that teachers raise their voices above the recommended level of decibels (from 58 to 90.5 dB), which involves an important risk of suffering vocal cord injuries.14,41 Likewise, many authors16,28,42 have recognized that a lack of classroom behavioral management is linked to the development of voice disorders. In the study by Hern
andez,43 when discipline is poor, the teacher will be four times more likely to suffer from dysphonia, probably because teachers resorted to ineffective techniques to maintain order, such as forcing the voice or shouting. It has been seen that this type of phonatory practice is very common among teachers, as they do not know how to use natural resonances in an effective way, all too often injuring their vocal ligaments.44 Diverse studies2,26,27,30,36,45,46 confirmed that voice strain and being loud among teachers is one of the main causes of voice-related pathologies. Hence, numerous researchers7,28,47–49 recommend training in phonoaudiological techniques to teach the necessary skills to manage the voice in an acceptable way and, thus, to prevent possible problems with the vocal cords. However, Gassull et al50 indicate that voice training for students and professional teachers in Universities is scarce. Various authors have noted that teachers possess few corporal and voicerelated resources, such as training on speech disorders,20 postural alignment for voice production,51 or vocal function exercises, resonant voice exercises, relaxation, and yoga techniques,52,53 which leaves them with insufficient techniques to attend to and to satisfy such exhausting and rigorous voicerelated needs that the teaching profession requires.54 With regard to healthy habits, numerous investigations38,43,46,55 have identified excessive smoking and alcohol consumption as important risk factors for dysphonia because these two habits, either together or separately, produce less hydration of the respiratory tract, slight edema in the vocal cords, and reddening and irritation of the respiratory mucous. Neither does a definitive agreement exist between experts on the efficacy of the principal protective measures to counter voice disorders among professional voice users such as the example of healthy life styles (food, physical exercise, and so on).56 However, sleep disorders are further health-related habits associated with the emergence of morbid phoniatric symptoms.46 It appears that sleep facilitates recovery.10 For all these reasons, the objectives of this study are, on the one hand, to analyze the relation that exists between these aspects and phoniatric disorders among teachers. On the other hand, it establishes both the protective and the risk factors that best predict the emergence of voice pathologies among teaching professionals. Finally, it suggests a series of lines of action to contribute to the prevention of voice disorders among teachers.

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Protective and Risk Factors in Voice Strain

METHOD This study applied an analytical cross-sectional design in which the variable result (phoniatric treatment) and the variables of exposure (sociodemographic, working conditions, training behavioral, and so on) were simultaneously measured. Sample A total of 675 teachers from the Autonomous Region of Castile and Leon, Spain participated in this study. The average age of the sample was approximately 46.96 years (standard deviation ¼ 9.43) and the range fluctuated between 23 and 66 years. The sample comprised both women (59.2%) and men (40.8%). According to the statistics supplied by the Ministry of Science and Innovation and the Ministry of Education, the percentages of male and female teachers in Castile and Leon, Spain (from higher and further education and obligatory schooling) over the period of data collection were 35.96% men and 64.05% women, which reflect the same ratios as in this study. Instrument of measurement An ad hoc questionnaire was designed for this study that was self-administered. Its questions were prepared on the basis of the questionnaire that Jackson-Menaldi57 proposed for voice evaluation, divided into a series of thematic blocks, namely sociodemographic characteristics (sex and age), working conditions (educational level, working experience, material, weekly classroom hours, and class size), voice training (questions on voice training), perception of noisy environments, and vocal cord abuse (perceptions that teachers hold of the noise generated in the classroom, the capability to maintain order, and the use of some negative techniques for the development of voice disorders such as raising the voice), voice health (consulting a general practitioner [GP], otorhinolaryngologist, and/or phoniatrician, for voice problems, sick leave, and phoniatric treatments) and health-related habits (smoking, drinking, food, sleep quality, and sporting activity). The response scales were either nominal (eg, men/women, nursery/secondary/university, yes/no, a lot/a little/not at all, and always/a little/never) or ordinal (eg; between 0 and 5 years/between 6 and 10 years/between 11 and 15 years/more than 15 years). Procedures The questionnaires were delivered through two different channels either by post to each educational center or they were personally delivered. The information was collected at various educational centers in the Autonomous Community of Castile. These centers were chosen at random from among secondary schools, institutes, and universities, both private and public, which ranged from nursery education up to university studies. Participation was voluntary, and participants could withdraw from the study at any time. No social security number or other identification data were asked, and no invasive examinations were made. The project was conducted with the approval of each municipality’s school and colleges authorities.

261.e3

Statistical analysis The data obtained were processed with the statistical software program SPSS 18.0 (IBM SPSS statistics 18.0). Contingency tables were applied to analyze the associations between different variables and the phoniatric treatment, together with the statistical index c2 and the analysis of the standardized (adjusted) residuals. These analyses were also used to ascertain the existing relations between sociodemographic characteristics and working conditions with perception of noisy environments and vocal cord abuse. However, the logistical regression models were applied to investigate the causal factors of phoniatric treatments in teachers and to study what factors modify the probability of a particular outcome. We selected the odds ratio as the parameter to study the strength of the statistical association, as the study sample is not statistically representative of the population. This index tells us how many times the illness is more likely to be contracted in the presence of a particular factor rather than in its absence. The determined estimated significance level was P  0.05. RESULTS Our objective was to identify both risk and protective factors associated with phoniatric pathologies and consequently with their treatment. To do so, people who requested phoniatric treatment were contrasted with those who did not request this type of treatment. We selected phoniatric treatment as the dependent variable because it is the best proxy we have for the true incidence of vocal pathologies, as it reflects the greatest seriousness from among all of the variables under examination. Variables such as visits to the GP because of voice-related ailments and to the otorhinolaryngologist and the phoniatrician were ruled out as less-sensitive indicators of voice-related pathologies. Sick leave was also ruled out as a possible dependent variable because it was less restrictive than medical treatment. Moreover, we have confirmed that phoniatric treatment presents significant and positive correlations with the other indicators of phoniatric disorders. We found that 16.4% of the sample of teaching staff from Castile and Leon, Spain were once administered a treatment to cure voice disorders. With regard to the other indicators, 57% of the sample went to the family doctor because of voice ailments, 71% visited the laryngologist and/or phoniatrician, and 36.2% went on sick leave once because of voice-related ailments. In addition, the percentage of teachers who had not received any type of voice training is really high, at more than half of the sample (52.2%). Variables associated with phoniatric treatment With regard to the sociodemographic characteristics and working conditions, the comparative analysis indicated that phoniatric treatment was not associated in a significant way with either the sex or the educational level or the length of service or the number of teaching hours of the teachers. However, the analysis of adjusted residuals indicated that the number of nursery education teachers who have received some type of phoniatric treatment was higher than predicted, whereas the number of

261.e4 teachers with 6–10 years of teaching experience, who have followed phoniatric treatment, was statistically lower than the predicted frequency. The two variables related in a statistically significant way with phoniatric treatment are the subject that is taught and the size of the class. Analysis of the standardized (adjusted) residuals indicated that the number of teachers of physical education and sciences as well as the number of teachers with more than 20 students who have received phoniatric treatment is greater than the number that was statistically predicted, whereas the number of teachers of music and the arts who have received this type of treatment was statistically less than predicted. Voice training also has a very statistically significant relation with phoniatric treatment. Surprisingly, the number of teachers who have received voice training in speaking and who have received phoniatric treatment is greater than the predicted value, if both variables were independent. The perception of noise generated by students, the difficulties of maintaining order in the classroom, and the technique of relying forcing or raising their voice to maintain discipline in class are associated in a significant way with phoniatric treatment. In particular, the number of teachers who have followed voice therapy and who consider that their students speak a lot in class, who find it difficult to maintain order, and who force or raise their voice in class was higher than the predicted frequency. Among the healthy habits, the variables that are associated in a significant way with phoniatric treatment are: smoking, sleeping, and alimentary habits. In a surprising way, the number of teachers who have received phoniatric treatment and who say that they do not usually smoke or that they are careful about their diet was greater than the predicted value. On the contrary, the number of teachers who received phoniatric treatment and who slept well was lower than predicted (Table 1). Variables associated with the perception of noise and teaching techniques to manage behavior in the classroom In the earlier section, we have shown that voice disorders are associated with a series of perceptions among teachers such as the noise generated in the classroom by their students, lack of discipline, and a series of behavioral patterns that are harmful to the voice (forcing the voice). On the other hand, the data show that these perceptions and poor behaviors present a very significant and positive association (P < 0.001), structuring a constellation of perceptions and behaviors that are in turn associated with phoniatric treatment. Preciado26 noted the relation that exists between these aspects, in such a way that classroom noise that bothers most teachers obliges them to raise their voice to make themselves heard and to impose their authority. We analyzed the profiles of the teachers from our sample that presented these perceptions and risk behaviors, as when coupled with vocal abuse behaviors, they were all associated with voice disorders. The perception of noise generated by the students was associated in a statistically significant way with sex, educational

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level, length of service, the weekly number of teaching hours, and the subject that is taught. The analysis of adjusted residuals indicated that the number of teachers who believed that their students spoke too much during the classes was statistically greater than that predicted among men, nursery education teachers, teachers with little work experience (from 0 to 5 years), teachers of physical education and geography, and those who gave more than 16 hours of class weekly (Table 2). The difficulties of maintaining order in the classroom are related in a tendential way with sex and in a significant way with the educational stage, length of service, number of weekly teaching hours, and the subject matter. The data on the analysis of adjusted residuals showed that the number of teachers who confessed to having discipline problems in the classroom was statistically greater than that predicted among men, secondary school teachers, those with less than 10 years teaching experience, those who had a high weekly teaching load (between 16 and 20 hours), and teachers of plastic arts and geography (Table 3). Vocal cord abuse such as forcing or raising the voice was also found to be related in a statistically significant way with sex, educational level, length of service, teaching load, and the subject that is taught. The results from the analysis of the adjusted residuals made it clear that the number of teachers who use this unsatisfactory resource to maintain discipline in the classroom was greater than that statistically predicted among men; teachers of primary education; those with more than 15 years of teaching experience; those who impart more than 16 hours of class every week; and teachers of plastic arts, sciences, geography, and generalists (Table 4). Protective and risk factors in phoniatric treatments As our objective is to identify both the protective and the risk factors associated with phoniatric pathologies and by doing so their treatment, the people who received phoniatric treatment (a condition assigned a value of one) were contrasted with those who did not receive this type of treatment (assigned a value of 0). The relation between the factors and dependent variable (phoniatric treatment) was analyzed through logistic regression techniques where the magnitude of the association between the variables is determined by the odds ratio (OR). In the case of there being no relation between the dependent variable and the factor, the value of OR is 1, values more than ‘‘1’’ will define a ‘‘risk factor,’’ whereas values lower than 1 will be indicative of a ‘‘protection factor.’’ Likewise, the confidence intervals of 95% for the estimations of the ORs were calculated by using the standard errors of the regression parameters. In the first place, the raw ORs were calculated for each explanatory variable using simple logistic regression models and the number of contemplated predictors. A multiple logistic regression model was used to estimate the joint effect, taking the variable elimination method step by step, beginning with the model that includes all the variables without interactions (complete or principal effects model). The meaning of the eliminated variables was evaluated with the likelihood-ratio test between the nested models. In general, we should consider this to be an exploratory analysis of the data.

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Protective and Risk Factors in Voice Strain

TABLE 1. Teaching Staff Variables Associated With Phoniatric Treatments Variables Sex Men Women Educational level Nursery Primary Secondary University Work experience (y) 0–5 6–10 11–15 +15 Weekly classroom (h) 0–5 6–10 11–15 16–20 +20 Subject taught Physical education Music Plastic arts Sciences Arts Geography Support All Number of students in class Between 0 and 20 More than 20 Voice training Yes No Perception of student noise levels A lot A little/nothing Difficulties maintaining order Yes No Raising or forcing the voice Yes Not Consume alcohol Yes No Practice a sport Yes No Smoke Yes No Dietary habits Yes No Rest Yes No

Treatment (%)

c2/P Value

No Treatment (%) c

2

17.3 16.9

82.7 83.1

25 13.2 18.9 13.8

75 86.8 81.1 86.2

(1,645) ¼ 0.02;

P ¼ 0.888

c2 (3,600) ¼ 7.22; P ¼ 0.065

c2 (3,630) ¼ 5.29; P ¼ 0.152 20 7.1 16.7 17.9

80 92.9 83.3 82.1 c2 (4,620) ¼ 3.82; P ¼ 0.431

0 13.6 20 20 15.7

100 86.4 80 80 84.3

37.5 6.7 0 21.7 9.4 0 0 16.7

62.5 93.3 100 78.3 90.6 100 100 83.3

c2 (7,545) ¼ 35.05; P  0.0001

c2 (1,625) ¼ 4.78; P ¼ 0.029 9.5 18.3

90.5 81.7 c2 (1,665) ¼ 44.87; P  0.0001

26.6 7.2

73.4 92.8

25 10.3

75 89.7

c2 (1,650) ¼ 25.04; P  0.0001 c2 (1,650) ¼ 60.58; P  0.0001 36.7 10

63.3 90 c2 (1,655) ¼ 4.00; P ¼ 0.045

19.3 13.5

80.7 86.5 c2 (1,635) ¼ 1.27; P ¼ 0.259

20.8 16.5

79.2 83.5 c2 (1,670) ¼ 0.78; P ¼ 0.376

17.2 14.3

82.8 85.7

9.5 18.2

90.5 81.8

c2 (1,655) ¼ 4.73; P ¼ 0.030 c2 (1,665) ¼ 4.45; P ¼ 0.035 17.9 9.5

82.1 90.5 c2 (1,660) ¼ 12.74; P  0.0001

14.4 28.6

85.6 71.4

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TABLE 2. Variables Associated With the Perception of Student Noise Levels Perception of Student Noise Levels Variables Sex Men Women Educational level Nursery Primary Secondary University Work experience (y) 0–5 6–10 11–15 +15 Weekly classroom (h) 0–5 6–10 11–15 16–20 +20 Subject taught Physical education Music Plastic arts Sciences Arts Geography Support All Number of students in class Between 0 and 20 More than 20

A Lot

Little/Nothing

c2/P Value c2 (1,630) ¼ 4.39; P ¼ 0.036

45.3 37

54.7 63 c2 (3,590) ¼ 90.08; P  0.0001

81.3 43.2 36.1 17.2

18.7 56.8 63.9 82.8 c2 (3,620) ¼ 19.19; P  0.0001

60 46.7 16.7 40.2

40 53.3 83.3 59.8

0 9.1 0 46.2 56

100 90.9 100 53.8 44

c2 (4,610) ¼ 110.71; P  0.0001

c2 (7,535) ¼ 65.24; P  0.0001 77.8 42.9 50 21.7 29 100 0 39.1

22.2 57.1 50 78.3 71 0 100 60.9

42.1 39.4

57.9 60.6

c2 (1,615) ¼ 0.24; P ¼ 0.623

In Table 5, the results of 23 simple logistic regression analyses are presented; one for each factor that is contemplated. It may be seen that in 13 cases, the association between the factor and the variable result is statistically significant. Among these same factors, six are risk related and the other seven are protective factors. The risk factors to determine the position of the teachers who received phoniatric treatment, as opposed to those who did not receive this type of treatment, are listed in accordance with the magnitude of their effect: the perception that order is only maintained in the classroom with difficulty, having received voice training, the perception that students speak more in class, a class size of more than 20 students, and telling students to be quiet by raising or forcing the voice. Paradoxically, the people who said that they had healthy eating habits also presented a greater risk of following therapeutic treatment. This unexpected result may be because responsibility for personal dietary habits is related to other health-related practices, such as visiting the doctor for check-ups and undergoing therapy, as against other teachers that might also need treatment, but do not visit specialist doctors.58

In contrast, the protection factors associated with phoniatric treatment are: being a teacher of music, arts teacher or a generalist as opposed to teachers of physical education, having sufficient rest and sleeping well, and being a primary or university teacher as opposed to nursery school teachers. Surprisingly, teachers who confess to smoking presented a lower risk of phoniatric treatment. The explanation behind these data may reside in the unwillingness of many smokers to stop their addiction to nicotine and the fact of having to visit the doctor. The 58
study by Alvarez concluded that people with harmful life styles, such as smokers, visit the doctor less than smokers who lead more healthy life styles, and that might be because they are less sensitive to health problems. A multiple regression model was applied with a total of 13 variables to obtain the most parsimonious model to arrive at an acceptable explanation of the results, by only introducing those that gave statistically significant differences in the bivariate analysis (except in the case of secondary school teachers and science teachers). With this aim, voice training was not included in the questionnaire as, even if there was a specific question about the received courses in their formation stage

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Protective and Risk Factors in Voice Strain

TABLE 3. Variables Associated With Difficulties Over Maintaining Order in the Classroom Difficulties over maintaining order in the classroom Variables Sex Men Women Educational level Nursery Primary Secondary University Work experience (y) 0–5 6–10 11–15 +15 Weekly classroom (h) 0–5 6–10 11–15 16–20 + 20 Subject taught Physical education Music Plastic arts Sciences Arts Geography Support All Number of students in class Between 0 and 20 More than 20

Yes

No

26.9 20.5

73.1 79.5

c2/P Value c2 (1,625) ¼ 3.46; P ¼ 0.063 c2 (3,585) ¼ 40.05; P  0.0001

20 21.6 36.1 6.9

80 78.4 63.9 93.1

60 35.7 25 18.5

40 64.3 75 81.5

c2 (3,615) ¼ 31.37; P  0.0001

c2 (4,605) ¼ 65.17; P  0.0001 0 4.5 0 38.5 22.4

100 95.5 100 61.5 77.6 c2 (7,530) ¼ 34.12; P  0.0001

28.6 21.4 50 26.1 15.6 100 0 26.1

71.4 78.6 50 73.9 84.4 0 100 73.9 c2 (1,610) ¼ 1.09; P ¼ 0.296

19 23.8

as teachers, and despite the fact that the bivariate data proved this variable as a risk factor, this result is possibly originated because most teachers have received voice training as a type of phoniatric therapy, maybe creating an overlap between both variables. Apart from erasing the confusion in the results and in the interpretation, erasing this variable did not modify the results substantially. The logistic regression model, using a joint input analysis procedure, offered a significant adjustment index (2LL: 279.02: c2 (14) ¼ 91.07; P ¼ 0.0001) and produced an acceptable level of correct classifications of the typology (85.4%). The value R2 of Nagelkerke shows that 33% of the variation in the dependent variable is explained by the variables included in the model. From among the 13 factors included in the analysis, three were significant, one corresponded to risk factors, and one to protection (Table 6). The only risk factor related to phoniatric treatment was raising or forcing the voice. On the other hand, the following may be found among the protective factors: the fact of being a teacher of arts involves a protection factor for phoniatric

81 76.2

treatments, as opposed to being a teacher of physical education, and certain healthy habits such as sleeping well.

DISCUSSION A total of 16.4% of the teachers in Castile and Leon, Spain have been shown to present some sort of vocal pathology. This percentage was obtained with a restrictive indicator of voice disorders, which is having followed some type of phoniatric treatment, in a similar way to other studies. The prevalence indices of voice pathologies found by other researchers using this criterion fluctuate between a 5.9% and a 33%.59,60 Although the phoniatric therapy has been frequently used as an indicator of the presence of voice pathology, not all teachers with symptoms related to vocal use have sought treatment or professional help. Therefore, this study may underestimate their true prevalence in the teaching population compared with other indicators. Despite the subjective measures being valid and reliable methods of data collection, the use of more objective instrumental

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TABLE 4. Variables Associated With Inappropriate Voice Techniques: Forcing or Raising the Voice Forcing or Raising the Voice Variables Sex Men Women Educational level Nursery Primary Secondary University Work experience (y) 0–5 6–10 11–15 +15 Weekly classroom (h) 0–5 6–10 11–15 16–20 +20 Subject taught Physical education Music Plastic arts Sciences Arts Geography Support All Number of students in class Between 0 and 20 More than 20

Yes

No

c2/P Value c2 (1,635) ¼ 6.12; P ¼ 0.013

49.1 39.2

50.9 60.8 c2 (3,595) ¼ 34.21; P  0.0001

50 55.6 44.7 24.1

50 44.4 55.3 75.9 c2 (3,625) ¼ 15.70; P ¼ 0.001

60 33.3 25 46.2

40 66.7 75 53.8

0 9.1 30 56.1 53.1

100 90.9 70 43.9 46.9

c2 (4,615) ¼ 82.69; P  0.0001

c2 (7,540) ¼ 96.51; P  0.0001 55.6 33.3 100 56.5 18.8 100 50 59.1

44.4 66.7 0 43.5 81.3 0 50 40.9

40 44.2

60 55.8

c2 (1,620) ¼ 0.61; P ¼ 0.435

methods for a more accurate calculation of the prevalence of voice problems in teachers is recommended. Nevertheless, apart from the used criteria or the instrument applied for measuring, the prevalence of vocal difficulties among teachers indicates that vocal dysfunction is a significant problem in this professional group. Despite the high presence of voice problems, we have noted that a very high percentage of these teachers have received no type of training for the voice, as it is not a subject that is found in any of the current study plans for the specialist teacher training courses. Evident from this study is the exclusive attention that should be given to all aspects of the field of educational psychology that help the teacher to manage problems of lack of authority and noise generated by students, in a satisfactory way. Especially, using resources such as raising or forcing their voice to maintain the order within the class appears as the main risk factor in voice problems. As in the study from Angelillo et al,7 those teachers who have detected that lack of authority and who perceive that their students speak during the classes are those who resort most to harmful strategies for the speech apparatus, seeking to impose themselves through raising and

forcing the voice, in such a way that they present a greater likelihood of suffering from voice disorders. Also special attention does have to be given to the classroom size and to the educational cohort with which the teacher works, as the teachers with large-sized classes and that specialized in nursery education were those who received phoniatric treatment more frequently. The educational level should not be a reason to forget that primary and secondary school teachers also present phoniatric symptoms and that they should therefore receive specific types of training and care with regard to preventive measures and voice care. This training should cover the specific problems of each teaching group; although the main problem in nursery education that teachers face is the noise generated by their pupils, teachers in primary resorted to raising and forcing their voice, and teachers in secondary education face problems of discipline that are not confronted in an acceptable way. We should not lose sight of the teaching staff with timetables that have a heavy teaching load. The number of weekly classroom hours is linked to the perception of noise and the unsuitable educational techniques to keep discipline in the classroom being precisely the nursery, primary, and secondary education

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261.e9

Protective and Risk Factors in Voice Strain

TABLE 5. Factors Related to Phoniatric Treatment. Complete Model. Simple Bivariate Logistic Regression Analysis Factors Sex (women vs men) Study level (nursery vs) Primary Secondary University Subject (physical education vs) Music Plastic arts Sciences Arts Geography Support All Work experience SE from  to + Number of hours/weeks teaching (from  to +) Average number of students (from  to +) Students speaking in class (no vs yes) Difficult to maintain order (no vs yes) Raise or force the voice (no vs yes) Voice training (no vs yes) Smoking (no vs yes) Drink (no vs yes) Eat well (no vs yes) Sleep well (no vs yes) Sport (yes vs no)

B

ET

Wald

P-Value

Odds Ratio

95% Confidence Interval

0.030

0.21

0.020

0.888

0.97

0.64–1.47

0.79 0.36 0.73

0.34 0.32 0.35

5.51 1.25 4.32

0.019 0.264 0.038

0.45 0.70 0.48

0.23–0.88 0.37–1.31 0.24–0.96

2.13 20.69 0.77 1.76 20.69 20.69 1.10 0.19 0.05 0.75 1.07 1.65 0.43 1.53 0.75 0.29 0.72 0.86 0.22

0.57 — 0.40 0.43 — — 0.41 0.14 0.10 0.35 0.22 0.23 0.21 0.24 0.35 0.25 0.35 0.25 0.25

14.11 0.00 3.76 17.14 0.00 0.00 7.24 1.88 0.23 4.60 23.69 53.50 3.97 39.71 4.55 1.27 4.29 12.21 0.78

0.0001 0.998 0.053 0.0001 0.999 0.999 0.007 0.171 0.630 0.032 0.0001 0.0001 0.046 0.0001 0.033 0.260 0.038 0.0001 0.376

0.12 0.00 0.46 0.17 0.00 0.00 0.33 1.21 1.05 2.12 2.92 5.21 1.53 4.63 0.47 1.33 2.06 0.42 1.24

0.04–0.36 0.00 0.21–1.01 0.07–0.40 0.00 0.00 0.15–0.74 0.92–1.60 0.87–1.26 1.07–4.23 1.89–4.49 3.35–8.11 1.01–2.33 2.87–7.46 0.24–0.94 0.81–2.19 1.04–4.10 0.26–0.68 0.77–2.02

teachers with an onerous teaching load who have most problems with the noise that their students cause and that resort more frequently to harmful behavior for the voice. Prevention programs should also take into consideration that the working experience affects differently the risk factors associated to the presence of voice problems. On the one hand, we have confirmed how teachers, as they gain further experience,

use more frequently a form of vocal cord abuse (raising or forcing the voice) increasing the risk of suffering phoniatric disorders of some sort or another at that age, although it would appear a priori that experience could be a protective factor against this type of problem. According to Scivetti,54 variable and prolonged exertion of the voice in speaking professions, added to inappropriate voice techniques, all too often mean

TABLE 6. Factors Associated With Phoniatric Treatment. Reduced Model. Multivariate Analysis of Logistic Regression Factors Study level (nursery vs) Primary Secondary University Subject (physical education vs) Music Sciences Arts All Average class size (from  to +) Students speak in class (no vs yes) Hard to maintain order (no vs yes) Raising/forcing the voice (no vs yes) Smoking (no vs yes) Eat well (no vs yes) Sleep well (no vs yes)

B

ET

Wald

P-Value

Odds Ratio

95% Confidence Interval

0.35 0.88 1.02

0.78 0.99 0.99

0.20 0.78 1.08

0.656 0.376 0.299

0.71 2.42 2.79

0.15–3.26 0.34–16.99 0.40–19.29

0.70 0.62 1.25 0.72 0.34 0.60 0.24 1.36 20.34 0.84 1.74

0.71 0.57 0.59 0.79 0.66 0.45 0.43 0.45 — 0.49 0.44

0.99 1.17 4.41 0.82 0.27 1.80 0.31 9.22 0.00 3.02 15.55

0.319 0.280 0.036 0.364 0.603 0.179 0.579 0.002 0.996 0.082 0.0001

0.49 0.54 0.29 0.49 0.71 1.82 1.27 3.89 — 0.43 0.17

0.12–1.97 0.18–1.65 0.09–0.92 0.10–2.30 0.20–2.58 0.76–4.36 0.55–2.95 1.62–9.35 — 0.17–1.11 0.07–0.42

261.e10 that teachers will strain their voices, as a way of compensating their incapability to manage the voice with an appropriate technique. On the other hand, lacking experience also negatively affects teachers, who do not have effective resources to face the excessive noise made by the students or to keep discipline within the classroom. Hence, P
erez and Preciado1 concluded that teachers with fewer years in the profession presented a higher predisposition toward the development of nodular pathologies, perhaps arising from less experience, stress, and the lack of voice techniques. Given that other protection factor associated with phoniatric treatment outside of the workplace is sufficient sleep, the awareness among teachers of caring for their voice should also be cultivated outside of working hours. This research presents two main limitations common to the cross-sectional studies.38 First, temporal relationships could not be assessed because of the cross-sectional design. Second, because of a lack of sufficient resources, we could not obtain comprehensive information about potential confounds and modifiers. A specific area where these limitations are evident is the effect of vocal training on the development of voice disorders. Contrary to what was found in prior studies, it has also been observed that in the case of having received voice training, most, probably, do so because of therapeutic referral. At present, therefore, we could assume that the voice dysfunctions that teachers present are in most cases treated once the ailment has presented itself. In a recent study carried out by Ohlsson et al,61 vocal training also appears as a risk factor for voice problems. Even when voice training should bring on a positive training effect on the voice with increased vocal skill and awareness, our questionnaire does not bring sufficient information about what kind and the amount of voice training that they had received. On the issue of the relation between voice training and the presence of voice problems, more research is necessary to reach meaningful conclusions. CONCLUSIONS In conclusion, our study demonstrated that voice disorders are common among teachers in Spain. Teachers who use a loud speaking voice, work in noisy classrooms, with large-sized classes, specialized in nursery education, teach physical education, and bad sleep are at greater risk of associated voice disorders. A remarkable percentage has never received any kind of voice training. Longitudinal studies and prospective cohort are urgently required to get more insight into the development of voice disorders, their work-related determinants, and the consequences of these voice disorders for functioning and work performance among teachers. Ultimately, the aim is to draw up a formative proposal adequate to the real needs and demands on the voices within the teaching profession for each of the educational contexts and stages. In doing so, the aim is to inform, raise awareness, and stimulate teaching staff to learn about their voice as an educational tool and as a motivating element of self-knowledge and professional and personal development.

Journal of Voice, Vol. 29, No. 2, 2015

This reaffirms the idea that for so long as spoken voice training is not integrated, in a coherent and disciplinary way, in previous and ongoing teacher training programs run by the Public Administrations and the relevant educational bodies, voice disorders and voice-related problems will continue to emerge and will persist among teachers, contributing to a large number of days off work, as well as health-related social costs in nonpriority phoniatric treatments, rehabilitations, surgical interventions, and so on that would be avoidable if the pertinent training and preventive measures were taken. Biographical Information S.U. is a contracted doctoral professor at the Department of Educational Sciences, University of Burgos and holds a doctorate in Psychology from the University of the Basque Country. Prominent among her lines of research is the study of predictive factors of risk behavior applied to various fields, among which, voice problems in teachers. She has also published and given conference presentations on this research question. J.C. is a titular university professor in the Area of Musical Expression at the University of Burgos. His doctoral thesis centered on investigating risk factors and the protection of phoniatric problems among teachers. In addition, he is the author of publications on voice technique and teaching and music pedagogy. He shares his teaching and research duties with his performances as a tenor. J.I. is a contracted professor with a doctorate in the Teaching of Spanish Language and Literature from the University of Burgos. His research and publications are centered on the scope of detection and solutions to phoniatric ailments among teaching staff, as well as in the fields of the teaching of literature to infants and young children, the encouragement of their reading skills, and the teaching of Spanish as a foreign language. I.I. is a lecturer of the Department of Personality, Psychological Assessment and Treatment at the Faculty of Psychology and Education in the University of Deusto (Spain). He is main researcher in the research team on Clinical and Health Evaluation, and he manages the clinical area in DeustoPsych (R + I + D in health and psychology). His main areas of interest are the assessment of health outcomes and the development of assessment tools. REFERENCES 1. P
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