Reduction in self-perceived vocal effort after photobiomodulation in a group of women without vocal problems: a brief communication

ABSTRACT

Purpose  To present initial results of an ongoing research about the effects of photobiomodulation (PBM) and inactive laser (placebo) on self-perception of vocal effort in women without voice complaints.

Methods  The participants were randomly divided in two groups: CG (Control Group - inactive laser); EG (Experimental Group - application of 9J per point of low-intensity laser in infrared wavelength). Vocal samples were recorded according to the CAPE-V protocol, numbers (1-20) and months of the year. During these tasks, the participants were guided to realize their self-perception of vocal effort, that was measured using the Borg CR10-BR Scale adapted for vocal effort applied before and after each intervention. Descriptive and inferential statistics were performed. The Shapiro-Wilk test didn't confirm the normality of the data, so the Wilcoxon test was used for intra and inter group comparisons (p-value<0.05).

Results  The total sample was composed of 20 women (18-45 years old), without voice complaints, with mean age of 28,6 years (SD=6,71) in the CG and 27,1 (SD=6,57) in the EG. CG showed a significant mean reduction in BORG scale scores (p=0.031) between pre and post intervention, as did EG (p=0.020). There was no statistically significant difference in the comparison between the two groups.

Conclusion  There was a general reduction in the self-perceived vocal effort in the pre and post intervention for both groups. A placebo effect was observed in the CG. No one reported a worsening of self-perceived vocal effort after PBM.

Keywords:
Speech, language and hearing sciences; Voice; Low-level light therapy; Laser therapy; Placebo effect