Development and usability of biofeedback system for water resistance therapy using sensor

Purpose: The purpose of this study was to develop a water cup device for voice therapy as a biofeedback device for water resistance therapy (WRT), one of the semi-occluded vocal tract exercises (SOVTEs) using sensors. In addition, we explore the usefulness of the system for training in voice therapy by implementing water resistance phonation through newly developed devices.Methods: Using Arduino, the water resistance value was measured using a water level sensor, and a system was developed to visually implement the water resistance value and duration of exhalation and vocalization according to the change in water level caused by bubbles. Visual feedback was provided using LED sensors that represent colors according to the height of the water level. The WRT step was performed on six normal adults (male 3 and female 3) to implement changes in water level change amplification rate according to tube diameter and depth, and quantitatively analyzed.Results: The experiment showed that different LED colors were displayed depending on the resistance value of the water level. The LED’s brightness decreased as the width of the silicone tube diameter became larger in the bubble according to the tube diameter. Moreover, compared to 5 mm or 7 mm, a tube diameter of 10 mm showed the lowest amplification rate, regardless of with or without phonation. A depth of 2 cm, with the tube tip submerged in water, demonstrated the lowest amplification rate with or without phonation, compared to 4, 7, and 10 cm.Conclusions: The newly developed cup device for water resistance therapy was easy to give visual feedback according to changes in water level and helped to identify objectively by quantifying the performance of the target. This system may help clinicians and patients not only in clinical situations but also in practice at home during voice training.