Biofeedback in dysphonia - progress and challenges.

Introduction: There is evidence that all the complex machinery involved in speech acts along with the auditory system, and their adjustments can be altered.

Objective: To present the evidence of biofeedback application for treatment of vocal disorders, emphasizing the muscle tension dysphonia.

Methods: A systematic review was conducted in Scielo, Lilacs, PubMed and Web of Sciences databases, using the combination of descriptors, and admitting as inclusion criteria: articles published in journals with editorial committee, reporting cases or experimental or quasi-experimental research on the use of biofeedback in real time as additional source of treatment monitoring of muscle tension dysphonia or for vocal training.

Results: Thirty-three articles were identified in databases, and seven were included in the qualitative synthesis. The beginning of electromyographic biofeedback studies applied to speech therapy were promising and pointed to a new method that enabled good results in muscle tension dysphonia. Nonetheless, the discussion of the results lacked physiological evidence that could serve as their basis. The search for such explanations has become a challenge for speech therapists, and determined two research lines: one dedicated to the improvement of the electromyographic biofeedback methodology for voice disorders, to reduce confounding variables, and the other dedicated to the research of neural processes involved in changing the muscle engram of normal and dysphonic patients.

Conclusion: There is evidence that the electromyographic biofeedback promotes changes in the neural networks responsible for speech, and can change behavior for vocal emissions with quality.