Vocal Health of Choral Singers from Kenya and the United States: Dysphonia and Vocal Fatigue in Relation to Musical Genres

The purpose of this mixed-methods study was to investigate the vocal health of choral singers from Kenya and the United States and to determine whether genre (classical choral, traditional Kenya, and Contemporary Commercial Music [CCM]) had any impact on healthy vocal production, particularly as it related to vocal fatigue. Participants were adult singers (N = 94) in two semi-professional choirs, the Nairobi Chamber Chorus (NCC) from Kenya (n = 25) and the Festival Singers of Florida (FSOF) from the United States (n = 69). Singers’ perceived overall vocal health was measured using multiparametric clinical self-reporting instruments and acoustical assessment. Singers’ level of dysphonia was assessed using the Singing Voice Handicap Index (SVHI) (Cohen et al., 2007), and the overall speaking voice was assessed using the Voice Fatigue Index (VFI) (Nanjundeswaran et al., 2015) which measured both vocal fatigue and potential pathology in the vocal mechanism. VoxMetria (1.0.7, CTS Informática, Pato Branco, Paraná, Brazil) was used as an acoustical assessment to provide further analysis of the quality of each participants’ voice by measuring Irregularity (jitter and shimmer) and Glottal-to-Noise Excitation (GNE). Singers’ vocal fatigue while singing various genres was assessed with the self-reporting Ability to Sing Easily (EASE) (Phyland et al, 2013) while employing the stylistic techniques performed in varying genres including Western choral music, traditional folk choral music, and choral genres within the realm of CCM. Singers also completed a questionnaire which provided demographic information, vocal training, genres performed, physiological aspects of the voice, vocal loading and hygiene behaviors, and a medical background as it pertains to their vocal health. This study also included interviews of four music educators from within each ensemble, selected using a stratified randomization process. Those interviewed had their voices analyzed using the CAPE-V analysis (ASHA, 2006). Quantitative results indicated that participants from both ensembles were vocally healthy overall as it related to their speaking and singing voices. Participants from FSOF expressed concern regarding their own vocal dysphonia, but all dysphonia measures indicated overall vocal health. Participants from NCC expressed less concern regarding personal dysphonia. While both groups were within the normal ranges for SVHI and VFI 2 scores measuring physical discomfort, NCC participants were significantly higher than FSOF participants. Irregularity (i.e., jitter and shimmer) scores were significantly higher in NCC singers than FSOF participants, indicating dysphonia. GNE scores for both ensembles were within the normal range, though FSOF participants showed significantly higher scores, indicating less breathiness in the tone, which is considered healthier. Results from the singer questionnaire indicated that aspects of vocal training, physiology, vocal loading, vocal hygiene, genres performed, and pathology within the vocal mechanism played a significant role in predicting the overall health of singers. Both ensembles had a high percentage of music teachers (NCC 40%, FSOF 88%). There was not a significant difference between music teachers and non-music teachers as it related to ensemble in overall vocal health. Regarding effect of genre on vocal fatigue as measured by the EASE, both choirs became less fatigued as they sang through the three genres (traditional and contemporary choral, CCM choral music, and folk and traditional folk music). FSOF was significantly less fatigued than NCC participants after 106 minutes of singing. Regarding genre, NCC participants’ fatigue increased when singing CCM choral music, and then significantly decreased when singing traditional folk music from Kenya and other African nations. Qualitative results indicated that participants from both NCC and FSOF had a similar understanding regarding the definition of healthy singing, though members from NCC focused primarily on concerns regarding range, endurance and avoiding undue strain and FSOF participants focused more on tension free, supported, and resonant singing. Music educators in both choirs highly valued singing in multiple genres and chose repertoire accordingly. They discussed various vocal techniques used when singing across genres. Music educators from NCC sang very differently when using their “natural” voice for traditional folk music and “rounded” singing for choral, CCM, and Bel Canto singing styles. Participants interviewed from both groups addressed the concern of sustained singing in extreme ranges and the vocal demand of blending their voices in a choral ensemble, indicating that these factors were more of a contributing issue to vocal fatigue than genre considerations. There were mixed results from participants in both groups regarding how they addressed vocal technique and vocal health in their own ensembles, especially as it related to genre and programming. The findings from this study indicate that trained semi-professional choral singers without indications of dysphonia can sing in these three genres without becoming fatigued. Implications from this research include creating a validated instrument for clinical and educational use that can be used to assess vocal health by analyzing the speaking voice, singing voice, and acoustical properties of the voice, which include assessment of vocal training, physiology, vocal loading, vocal hygiene, genre, and pathology of the voice