Objective: To verify the effects of photobiomodulation (PBM) on the self-perception of vocal effort, acoustic measures and in a group of women without voice complaints.

Methods: Clinical, randomized and blind study. Participants were randomly divided into four groups: CG (Control Group – inactive laser); G1 (Group 1 – laser – 9J per infrared wavelength point at three equidistant points, starting from the laryngeal prominence); G2 (Group 2 – voiced trill technique for 3 minutes in habitual tone) and G3 (Group 3 – laser under the same conditions as G1 followed by voiced trill technique under the same conditions as G2). The Vocal Fatigue Index Protocol was applied before interventions in all groups; voice samples and responses to the BORG CR10-BR scale adapted for vocal effort were collected before and after the interventions. To analyze the samples, the AVQI, ABI and CPPS acoustic measures were extracted and auditory perceptual assessment (APA) of the overall severity of voice quality was carried out using the CAPE-V protocol (two judges with clinical experience in Voice). Once the normality of the data was confirmed, the paired Student's T Test (p<0.05) was used to compare the means of the variables between pre and post-intervention periods for each group and the intra and inter-judges agreement (APA) was evaluated (Kappa).

Results: 40 women without voice complaints participated, aged between 18 and 45 years (10 in each group). Only the BORG CR10-BR Scale indicated a reduction in scores between the pre and post periods for the CG (p=0.011), G1 (p=0.009) and G2 (p=0.008), with G2 showing a greater mean difference between the pre (1.65 – very slight) and post (0.80 – just noticeable) moments. The acoustic measures and APA indicated voices within normal variability, but without statistically significant differences.

Conclusions: For this sample, both groups that received the laser and the group that received the inactive laser, presented the immediate effect of reducing the self perceived vocal effort. Larger samples can contribute to a broader study of PBM in voice studies.