Understanding and improving vocal health : a tiered investigation into a group of Occupational Voice Users

Abstract

Background: Currently, more than one-third of the global workforce requires integrity of the voice to meet their occupational demands and are therefore considered professional voice users (PVUs)/ occupational voice users (OVUs) (Pomaville et al., 2019; Reed & Sims, 2017). Despite expected vocal load and demand, voice quality, and vocal sophistication differing between professions, all OVUs depend on vocal endurance (Rangarathnam et al., 2018). OVUs’ livelihoods depend partially or completely on their voice, yet the prevalence of voice disorders in OVUs is rising due to increased daily vocal demands. In an effort to prevent voice disorders in OVUs, the implementation of Vocal Hygiene Education (VHE) programmes is endorsed (Achey et al., 2016; Pomaville et al., 2019; Porcaro et al., 2019; Rangarathnam et al., 2018). The main goals of VHE programmes are to educate individuals regarding practices to ensure vocal health, balancing muscles for optimal vocal production, and keeping the tissue free of lesions and pathology, particularly for OVUs (Faham et al., 2016; Pomaville et al., 2019). Thus, VHE is a therapeutic and preventive approach based on behaviour modification thought to preserve and protect the vocal fold tissue and normal vibratory characteristics of the vocal folds (Faham et al., 2016; Pomaville et al., 2019). Consequently, VHE programmes require vocal modifications in daily routines to directly improve vocal health, including education regarding voice production, identification and elimination of phonotraumatic behaviours, the importance of adequate hydration and healthy strategies for voice production (Achey et al., 2016; Pomaville et al., 2019; Porcaro et al., 2019; Rangarathnam et al., 2018). Voice use reduction is central to Vocal Hygiene (VH) programmes (Van Der Merwe, 2004) and can be used as a method to modify daily routines aimed at directly enhancing vocal health. Yet, literature reviews show the absence of a standard protocol for voice rest or reduction (Kaneko et al., 2017). The importance and rationale behind novel approaches to the prevention and treatment of voice disorders in OVUs is well established and supported by the International Classification of Functioning, Disability and Health (ICF) framework (WHO, 2001), as occupational participation is threatened and through this, quality of life of the OVU.

14 Study Aim: To understand and improve vocal health through a tiered investigation of vocal hygiene education, vocal demands, perceptions, knowledge, and voice use reduction in occupational voice users. This study had the following three research objectives: ● To systematically review the existing evidence on the effect of VHE on the voice quality of PVUs according to the PRISMA-P (Moher et al., 2015) guidelines. ● To describe daily vocal demands, perceptions, and knowledge as reported by OVUs in South Africa. ● To determine the effect of the Voice Use Reduction (VUR) programme (Van Der Merwe, 2004) on voice quality and vocal fatigue in OVUs. Method: A tiered approach was employed to achieve the main aim of the study and the study objectives. In study one, a systematic review was conducted utilising the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA-P) guidelines. Five databases were searched using the keywords “vocal hygiene”, “vocal hygiene education”, “vocal health”, “vocal quality”, and “voice quality” with Boolean phrases “AND” and “OR”. Twenty-three studies that met the eligibility criteria were included. Scoring was based on the American Speech-Language- Hearing Association’s levels of evidence and quality indicators, as well as the Newcastle Ottawa Scale (NOS) for assessing the risk of bias. In study two, a descriptive, cross-sectional research design was employed by means of a survey on vocal demands, perceptions, and knowledge in OVUs. A total of 100 both male and female OVUs (call centre agents, teachers, lecturers, singing students, and performing arts students) were invited to complete the vocal demands survey using a snowball sampling technique. For study three, a within-subject, quasi-experimental, pre-test post-test research design was performed on 30 OVUs who were randomly sampled from the initial 102 OVUs in study two. Perceptual and acoustic outcome measures were employed pre- and post-implementation of the VUR, including the GRBASI 4-point rating scale, jitter, shimmer, HNR, MPT, frequency min and max, intensity min and max, and the dysphonia severity index (DSI) and perceived vocal fatigue (VF) using the Vocal Fatigue Index (VFI).

15 Results and discussion: The systematic review revealed three main themes: low awareness of vocal hygiene or insufficient vocal hygiene education is linked to self- reported acute and chronic voice symptoms as well as a greater perception of voice handicap amongst professional voice users (n=4;17%). When voice training or vocal hygiene education was adequate this led to positive voice outcomes (n=10; 43%). Vocal hygiene education is more effective when combined with direct voice therapy (n=6; 6,26%). Study two discovered that slightly more than half of the participants (n= 55; 55%) reported using their voice for work 36,5 hours a week on average (SD= 15,5, range: 33-40). Participants reported that, on average, their daily voice use is 6,3 hours (SD= 2,7) for work and the majority (n=81; 81%) reported a decrease in voice quality after work. Three-quarters (n=75; 75%) also reported vocal fatigue at the end of the day. Approximately one-third (n=33; 33%) reported being exposed to environments where they are expected to shout, scream or cheer loudly. More than half of the participants (n=61; 61%) reported that they have previously received vocal health education but (n=40) 40% reported that they felt this training was insufficient. High vocal demands are significantly correlated to an increase in perceived vocal handicap rs=0,242 (p=0,018), tiredness of voice rs=0,270 (p=0,008), physical discomfort rs=0,217 (p=0,038) as well as how occupational voice users experience improvement of symptoms with rest rs= -0,356 (p<0,001). Other risk factors highlighted by occupational voice users are the ingestion of liquid caffeine, alcohol, and carbonated drinks, smoking or the presence of chronic cough, chronic laryngitis and gastroesophageal reflux disease. In study three it was found that pre- and post- test outcomes show significant (p <0.001) decreases in G (Grade of hoarseness), R (Roughness), A (Asthenia), S (Strain), and I (Instability) in post-test. Perceptual normality in all of these areas increased significantly (p <0.001). Acoustic measures revealed significant (p < 0.05) decreases in Jitter%, Intensity (dB) Min and DSI scores as well as significant (p < 0.05) increases in MPT /a/,/s/ and /z/, Frequency (Hz) Max, and F (Hz) Max, indicating improved voice quality at post-test. The VUR programme positively affected and improved OVUs’ perception of VF in the areas of tiredness of voice and physical discomfort. Conclusion: The most significant contribution of the project may be that it provides the first known comprehensive description of the outcomes of the VUR Programme on voice quality and vocal fatigue. A novel description of the voice profile of OVUs

16 requiring voice rehabilitation is introduced. The study adds to the knowledge base of all speech-language therapists, not only in South Africa and those from LMICs, as literature has shown voice profiles and symptoms of OVUs to be similar regardless of demographic area or income status. When approaching OVUs, clinicians are encouraged to make use of a combination of direct voice therapy and vocal hygiene accompanied by the use of sustainable programmes, such as the VUR to help develop healthier use of the voice, foster patient autonomy, facilitate healing and prevent further/future injury. Voice rest has been proposed to decondition the voice whereas voice therapy is thought to recondition the voice (Haben, 2012) and, should therefore be used congruently. These findings serve to promote vocal health consciousness and awareness for preventive voice care initiatives in this unique population, through the use of VHE and the VUR programme.