Study design, materials and methods
This research was designed as an observational, cross-sectional study. Ten males and ten females aged between 19 and 25 years were included in the study. Socio-demographic informations of the participants were recorded. The Voice Handicap Index Short Form and GRBAS scale were used to assess the voice problems of the participants. PFM strength and Transversus Abdominus (TrA) muscle strength were evaulated with by surface-electromyography biofeedback device (Neurotrac® Myoplus 2 Pro) at rest (pre/post-work) and during five 10-second contractions. Following the participants' explanation about the location and how to contract the PFM, superficial electrodes were applied on the skin to the PFM and TrA muscle. Voice acoustic characteristics (F0, jitter, shimmer, harmonic to noise ratio) and aerodynamic characteristics (maximum /a/ phonation duration, /s/ phonation duration, /z/ phonation duration, s/z ratio) were assessed by Multi Dimensional Voice Program and CSL 4500 B Computerized Speech Lab device, respectively. Spearman correlation analysis was used to evaluate the correlation between the parameters. Significance level in statistical analysis was accepted as 0.05.
Results
The mean age and mean body mass index of the participants were 20.5±1.88 years and 22.3±2.20 kg/m2, respectively. It was found that mean maximum /a/ phonation duration was 16.58±5.51 and, mean shimmer was 2.95±1.15. During 10-second contractions, it was observed that the average PFM strength was 8.12±3.26, while the average strength of TrA muscle was 19.1±14.3. There was a positive moderate correlation between maximum /a/ phonation time and TrA muscle strength (p=0.011, rho:0.561). Negative moderate correlation was seen between s/z ratio and TrA muscle strength (p=0.05, rho= -0.444). However, no correlation was found between other parameters.
Interpretation of results
According to the findings of our study, it was observed that participants primarily used the TrA muscle when asked to contract their PFM. Strong TrA muscles have been linked to longer phonation durations and fewer vocal disorders. The relationship between PFM and the aerodynamic and acoustic characteristics of voice may be clarified with a larger sample size.
Concluding message
Generally, individuals could not fully perceive the exact location of their pelvic floor muscles, so even if their muscle strength is good, they cannot contract them sufficiently and tend to use their abdominal muscles more. It is important to provide awareness educations and biofeedback device training that individuals may understand how to contract and relax their pelvic floor muscles correctly. Since speech occurs during the expiratory phase of respiration, the diaphragm maintains tension and the abdominal muscles also work actively. As a result, individuals with stronger TrA muscles could be able produce sound for longer. Determining the actual relationship between PFM and phonation will be useful in developing rehabilitation techniques for individuals with PFM dysfunction and voice disorders.