Dysphonia in teachers: is it only a matter of voice misuse?

Patients and methods Patients Population of study was 250 teachers working in primary schools in Fayed Educational Management, which are governmental schools. Both male and female teachers were included. Th ey were involved in the active teaching process and had spent in this teaching process at least 1 year. Th eir age ranged from 22 to 50 years (mean age 36.12 years). In addition, 30 normal agematched and sex-matched individuals were taken as the control group for acoustic measurements. Dysphonia in teachers: is it only a matter of voice misuse? Asmaa Ahmed Abdel Hamida, Hossam Mohammed Eldessoukya, Nagy Micheal Iskenderb, Elham Mo’men Hassanc


Introduction
Voice serves an important function of regulating social communication and interactions [1]. Dysphonia is expressed as any diffi culty or change in voice emission that interferes with natural voice [2].
Th ere has been growing interest during recent years in studying the relationship between dysphonia and teaching work. Prior research indicates that teachers represent a high-risk group with respect to the development of voice problems [3].
Th e vocal loading that occurs in the daily life of teachers has several causes; long teaching hours, poor room acoustics, and bad air quality are seen as the leading causes of voice problems in teachers. Psychological and emotional aspects may also contribute to voice disorders [4,5].
Allergies may cause excessive mucous and edema of the vocal folds; edema and excessive mucous on the vocal folds have a negative eff ect on the voice quality [6]. In addition, it causes an increased need for throat clearing and coughing [7]. Similarly, Issing et al. [8] has evaluated and reported negative eff ects of pathological acid refl ux on the mucosa of the larynx.

Aim
Th e aim of this study was to answer the study question whether dysphonia in teachers is due to voice misuse only or there are other underlying factors and to determine the prevalence of dysphonia in the study sample and laryngeal pathology underlying dysphonia in teachers.

Patients
Population of study was 250 teachers working in primary schools in Fayed Educational Management, which are governmental schools. Both male and female teachers were included. Th ey were involved in the active teaching process and had spent in this teaching process at least 1 year. Th eir age ranged from 22 to 50 years (mean age 36.12 years). In addition, 30 normal agematched and sex-matched individuals were taken as the control group for acoustic measurements.

Aim
This study investigated dysphonia in a sample of Egyptian teachers and determined the prevalence of dysphonia in the sample under study.

Patients and methods
The study was carried out by applying a questionnaire to 250 primary school teachers in Fayed city. The questionnaire included three main groups of questions that indicate the presence or absence of dysphonia, gastric re ux, and allergy, in addition to questions about personal and teaching data. The participants who reported that they suffer from dysphonia were transmitted to the second step of the study, which is acoustic analysis for their voices and laryngoscopic examination for their larynges.

Inclusion criteria
(1) Teachers with almost similar voice misuse during teaching hours/day (4-6 h), with a teaching period more than 1 year. (2) Th e same type of schools (governmental), the same teaching stage (primary schools), and nearly the same environmental conditions.

Study sample
Sample type: Simple random sample was selected by choosing teachers from a given list (every even number), obtained from records of directorate of upbringing and education of Ismailia, then the schools where they work were identifi ed to reach them through school visits.
Sample size: A sample of 250 primary school teachers was included, 39 (15.6%) male teachers and 211 (84.4%) female teachers. Th e sample size was obtained through the following statistical equation: where Z /2 is 1.96 for 95% confi dence level, P is the prevalence of dysphonia (28.8%), and E = SE × P × Z /2 [standard error (SE) = 0.1].

Data collection
Data were collected through the following: (1) Protocol of voice assessment applied in Kasr Al-Aini Hospital was carried out for those participants who reported that they are dysphonic by the applied questionnaire. related to allergic rhinitis symptoms that have been identifi ed in the peer-reviewed literature as having the greatest diagnostic value. It will not produce a defi nitive diagnosis, but they are highly suggestive of allergic rhinitis [9].
Questions that indicate presence or absence of gastric refl ux were obtained from the refl ux symptom index ( RSI) by Belafsky et al. [10] who consider an RSI greater than 13 to be abnormal. Hence, in the present study, the teacher is considered positive for refl ux when he or she has a RSI score greater than 13. (c) Auditory perceptual assessment ( APA) was performed by two phoniatricians using the 'modifi ed GRBAS scale' [11] as following: Dysphonia: overall grade, character (strained, leaky, breathy, or rough), pitch (overall increase, overall decreased, or diplophonia), register (habitual register, register break, or tendency of vocal fry at the end of phrases), loudness (excessively loud, excessively soft, or fl uctuating), glottal attack (normal, hard, or soft), associated laryngeal functions (cough, whisper, and laughter, which may be aff ected). Th e APA was documented by voice recording, which was carried out in a sound-treated room with a high fi delity computerized audio recording system. (2) Clinical diagnostic aids: A laryngeal videoendoscopy was carried out using 90° rigid endoscope of a Karl Storz endoscopic set (Germany). It was performed for dysphonic participants to fi nd out why are they dysphonic.

(3) Additional instrumental measures:
Acoustic analysis: the acoustic analysis was performed using the voice analysis software Praat version 5.3.40 (Paul Boersma and David Weenink, Th e University of Amsterdam, Th e Netherlands) [12]. [Praat (the Dutch word for 'talk') is a scientifi c computer software package] after optimizing it for voice analysis. Jitter (%), shimmer (dB), and harmonic-to-noise ratio were obtained.

Data management and statistical analysis
Th e collected data were revised, summarized, and then analyzed by statistical package for the social science (SPSS, version 16; SPSS Inc., Chicago, Illinois, USA).
Data were calculated and presented with corresponding 95% confi dence intervals. Parametric data were expressed as mean ± SD and nonparametric data were expressed as number and percentage of the total. Th e analyzed data were then presented into tables and graphs.

Ethical considerations
Our study was ethically approved by obtaining the agreement of the following: (1) Postgraduate and ENT Department.
(2) Ministry of Upbringing and Education.

Results
Data of this study were analyzed statistically and they show the following results: (1) Data of the participants included age, sex (Fig. 1), teaching years, and teaching hours (Tables 1-7). (2) Dysphonia distribution and its relationship with age and sex (Tables 8-10). (3) Allergy distribution and its correlation with dysphonia (Tables 11 and 12). (4) Refl ux distribution and its correlation with dysphonia (Tables 13 and 14).
Sex distribution among subjects Comparison between acoustic analysis results of the control and dysphonic groups (Table 17).

Discussion
Voice function is a complex phenomenon and has an undisputable relationship with the voice load and occupational demands [13].
In this study, there were 250 teachers in total, consisting of 84.4% female teachers and 15.6% male    Vocal fold polyp

Figure 3
Vocal fold hemorrahge teachers (Fig. 1), which is in agreement with the study by Laukkanen and colleagues who stated that female teachers are a majority in the teaching profession.
Th is study shows that the prevalence of dysphonia in the sample under study -according to self-subjective impression of teachers -is 23.2%, which is a relatively high prevalence (Table 8). Th e reason is because teachers often spend a long time talking loudly in noisy environments and in stressful situations [14]. In addition, there is a general agreement that vocal load is the major cause of voice problems in the teaching staff [2].
Diff erent studies conducted have shown that the prevalence of voice fatigue in teachers varies from 18 to 32% [3,15,16]. Th e prevalence of dysphonia is quiet close to that of the present study.
Th e prevalence in other studies ranges from 50 to 88% [17]. Th is is so far much higher than that of the present study.
Varying results in these papers may be explained by diff erences in defi ning duration of the condition, frequency of symptoms, and diff erences in sample size.
APA of teachers with complaint of dysphonia revealed variable degrees of dysphonia. Acoustic analysis confi rmed APA fi nding by abnormal jitter, shimmer, and mean harmonic-to-noise ratio values as compared with the control group (Table 17).
Videolaryngoscopic examination was performed in those participants who consider themselves to be dysphonic -by questionnaire -to fi nd out why are they dysphonic. It shows that 86.2% of dysphonic patients show pathological lesions in their vocal folds, whereas 13.8% of them show free vocal folds (Figs 2-6  and Table 16).
Th e presence of acoustic analysis changes even without the presence of structural pathology could be explained by that dysphonia in the absence of laryngeal structural pathology may precede laryngeal structural pathology [18]. In addition, what may seem to be functional dysphonia on evaluation has been suggested by some studies to possibly be secondary to microorganic disease instead (organic disease not detectable on examination) [19].
Th e explanation for this dysphonia is because teachers often spend a long time talking loudly in noisy environments and in stressful situations [14]. Th ese talking styles lead to increased glottal closure, which elevate vocal fold impact stress resulting in functional voice problems and vocal fold pathologies, especially vocal fold nodules [20].
Th ese are the same reasons for Tavares and Martins [21], who stated that vocal overuse or misuse during teaching over a period of time is a primary cause of voice disorders and vocal fold pathologies. Th is result is in concordance with another study, which showed that teachers are more susceptible to aphonia, edema, polyps, and nodules than nonvocal professionals [22].
Th is study revealed that teaching years has no relationship with the development of dysphonia (Table 7). Th is could be explained by that younger teachers reported greater vocal diffi culties due to working longer hours HNR, harmonic-to-noise ratio; P < 0.01, highly signi cant.

Figure 5
Arytenoid edema and vocal fold erythema and having poorer vocal hygiene techniques than their older, more experienced peers [23]. Th is result agree with the study conducted by Simberg et al. [24], who reported that length of teaching experience has little correlation with the frequency of voice disorders. In addition, other studies reported that old age is not a risk factor for dysphonia [22]. However, this result disagrees with studies showing that one of the risk factors for the development of dysphonia is being older or having more years of teaching experience [3,25].
Th is study revealed that there is a positive correlation between teaching hours/week and presence or absence of dysphonia (Table 6). Th is could be because of cumulative voice use [16]. As the vocal loading that occurs in the daily life of teachers has several causes, one of them is long teaching hours [4].
Concerning sex, this study revealed that there is no correlation between sex and development of dysphonia, which is unexpected (Table 9), as women have some physiological factors that predispose them to the development of voice problems, such as a glottic confi guration favoring bowing, hormonal infl uence on vocal qualities, and higher incidence of endocrinological diseases; in addition, women have shorter vocal folds and produce voice at a higher fundamental frequency. In addition, there is less tissue mass to dampen a larger amount of vibrations and lower levels of hyaluronic acid in the superfi cial layers of lamina propria, which decreases the tissue viscosity of the vocal folds and their shock-absorbing capabilities [21]. Th is result may be due to diff erence between male and female teachers included in this study with respect to number of teaching hours/week and number of teaching years.
Th is result disagrees with the study conducted by Smith et al. [22], who reported female sex as one of the risk factors for dysphonia, in addition to the study conducted by Laukkanen et al. [26], who revealed that female individuals have about twice as many voice problems as male individuals.
It also disagrees with previous studies that have been consistently reporting that female teachers have signifi cantly more voice problems than their male colleagues [17,27].
With respect to allergy, this study shows that there is a positive correlation between allergy and dysphonia (Table 12). It can be explained by that the mucous is heavier and more tenacious in allergic persons than in persons without allergy and interferes with the mucosal wave in the vocal folds [28]. Th is result agrees with the results of a survey by Roy et al. [3], who showed that the patients who had voice disorders reported respiratory allergies signifi cantly more often than those who did not have voice disorders. In addition, the results of two questionnaire studies showed that allergic patients have more frequently occurring vocal symptoms than patients in the control group [24,29]. However, this disagrees with the study by King et al. [6], who reported that the larynx of allergic patients is often normal.
Th is study showed that refl ux also has positive correlation with dysphonia (Table 14). Th is table shows that 60.3% of dysphonic patients are positive for refl ux. Th e explanation is that the delicate ciliated respiratory epithelium of the posterior larynx that normally functions to clear mucus from the tracheobronchial tree is altered by the gastric refl uxate, and the resultant ciliary dysfunction causes mucus stasis. Th e subsequent accumulation of mucus produces postnasal drip sensation and provokes throat clearing [30].
In addition, the direct refl uxate irritation can cause coughing and choking (laryngospasm) because of sensitivity infl ammation [30]. Th is combination of factors can lead to vocal fold edema, contact ulcers, and granulomas that cause laryngopharyngeal refl ux (LPR)-associated symptoms such as sore throat, globus pharyngeus, and dysphonia [31].
Th is result agrees with the results of Ross et al. [32] who reported that all patients with suspected LPR had signifi cantly increased abnormal perceptual voice characteristics in the form of musculoskeletal tension, hard glottal attack, glottal fry, restricted tone placement, and dysphonia.
In addition, Pribuisiene et al. [33] had reported that parameters including jitter, shimmer, normalized noise energy, voice handicap index, and phonetogram parameters were signifi cantly diff erent in patients with LPR.
In contrast, diff erent authors have shown that laryngeal fi ndings commonly attributed to refl ux laryngitis can be visualized in up to 64-86% of normal controls [34,35]. In addition, a structured review of randomized controlled trials has failed to detect a signifi cant advantage of proton pump inhibitors over placebo in the treatment of patients with refl ux laryngitis, which indirectly make the role of refl ux in dysphonia questionable [36].