Acoustic Parameters and Salivary IL-6 Levels in Overweight and Obese Teachers

Abstract

Either obesity or vocal loading task leads to elevation of proinflammatory cytokines such as interleukin 6 (IL-6). However, it is unknown whether vocal parameters after vocal loading are correlated with body mass index (BMI) or IL-6. We hypothesize that vocal loading induces an elevation of acoustic parameters of voice and salivary IL-6 in overweight and obese people. A total of 33 schoolteachers without any self-reported voice alterations were invited to participate in this study. Participants were classified according to BMI into normal, overweight, and obese groups. The vocal loading task consisted of loud speech (60-90minutes) in their classroom. Salivary and voice samples were taken before and after vocal loading. Perceptual and self-reported voice alterations and objective voice analyses were investigated. The relative concentration of salivary IL-6 was estimated by a colorimetric assay. Obese teachers showed a significant elevation in fundamental frequency value after vocal loading. In addition, reduction in harmonics-to-noise ratio (HNR) was observed in teachers with normal weight after vocal loading but not in overweight or obese groups. No significant correlation was observed between BMI and any of the acoustic parameters analyzed or salivary IL-6 levels. Furthermore, teachers who were overweight showed a significant increase in the salivary IL-6 levels after vocal loading. Interestingly, salivary IL-6 levels were positively correlated with HNR value in the overweight group after vocal loading. Excessive body weight is related to alterations in fundamental frequency and HNR. In addition, HNR, but not BMI, is associated with salivary IL-6 levels in overweight teachers.