Related Experiment Video
Updated: Sep 12, 2025
Construction and Characterization of a Novel Vocal Fold Bioreactor
Published on: August 1, 2014
Immediate Effects of Photobiomodulation in Vocally Healthy Individuals Undergoing Vocal Loading Activity: A
Rebeca Vila Nova de Araújo Torres1, Leonardo Wanderley Lopes1, Ana Celiane Ugulino2
1Department of Speech Therapy, Federal University of Paraíba - UFPB, João Pessoa, Paraíba, Brazil.
Objective:
To analyze the immediate effects of photobiomodulation (PBM) on vocal parameters of vocally healthy individuals subjected to a vocal load activity.
Methods:
This was a triple-blind, randomized clinical trial. Individuals who did not present with vocal complaints, vocal quality deviations, or structural or functional disorders in the larynx were recruited and randomly assigned to the EXPERIMENTAL group (laser) or PLACEBO group (control). Participants in the EXPERIMENTAL group received low-level laser PBM application, followed by phonation exercise into a straw with a rigid tube in the air for 10 minutes. The PLACEBO group received placebo PBM, followed by the same vocal exercise performed in the EXPERIMENTAL group. In both groups, the PBM application and the vocal exercise were performed immediately before a vocal load activity, which consisted of reading aloud standardized texts under exposure to an environmental "bar noise." All participants were assessed immediately before the intervention (T0) and after the proposed workload activity (T1).
Results:
No significant differences in auditory-perceptual evaluation or vocal self-assessment were observed between the groups at T1. However, there was a significant difference between the groups at T1 for the acoustic measures of high-frequency noise (Hfno) and H1-H2 obtained by the sustained vowel /a/ task, with higher values observed in the EXPERIMENTAL group. In the glottal-to-noise excitation ratio (GNE), measures were observed in the number counting task, with higher values observed in the PLACEBO group.
Conclusion:
The immediate effects of PBM on the vocal parameters of individuals subjected to vocal load are discreet and restricted to some acoustic indices. Individuals who received PBM showed an increase in the acoustic measure H1-H2 after the vocal load, which may suggest a reduction in the contact force between the vocal folds and, possibly, less vocal hyperfunction in the EXPERIMENTAL group.
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