Parkinson''s disease (PD) is a degenerative disease of the central nervous system that mainly affects the sensory and motor function. PD patients had difficulty in controlling their vocal pitch and loudness, poor self monitoring due to sensory disorder. Lax Vox voice therapy is a holistic approach, immediately correct and facilitate the function of the vocal mechanism in short time and also a cognitive method to give bio-feedback, producing bubbles with tube phonation into the water. Therefore, Lax Vox voice therapy can be useful for patients with parkinson’s disease to provide visual feedback. The purpose of this study was to investigate the effectiveness of a 6-week training program with the voice therapy "Lax Vox" for patients with parkinson’s diasease. A total of 10 patients (4 males and 6 females) with Parkinson'' s disease participated in this study. Voice therapy "Lax Vox" was carried out once a week for 6 weeks and therapy sessions were generally held once a week for 50 minutes performed by a speech-language pathologist. A silicone tube(35 cm length, 10 - 13 mm diameter) and a 500 ml water bottle were used. Lax Vox voice therapy consists of a total of six stages. The first stage consists of posture correction, relaxation and breath control and bubbles without phonation; the second stage is bubbles with phonation, the third stage is the finding the target voice, the fourth and fifth stages are improving the target voice, six stage is generalization. To assess the effectiveness of Lax Vox voice therapy, aerodynamic, acoustic evaluation, electroglottography(EGG), and Korean-version Voice Handicap Index(KVHI) - 10 were performed before and after voice therapy.
The results revealed that significant improvement in aerodynamic, acoustic evaluation, and Korean Voice Handicap Index(KVHI) - 10 was yielded following Lax Vox voice therapy. After treatment, significantly increased vital capacity(VC) and maximum phonation time(MPT), and reduced subglottal air pressure(Psub) were observed. The CPP, a measure of cepstrum, was significantly increased after treatment and the sAPQ and vFo in acoustical parameters of MDVP were significantly decreased. In addition, the Voice Range Profile(VRP) was extended and Korean version of Voice Handicap Index(KVHI) - 10 scored significantly lower.
Our study confirmed that significantly positive effects were found in respiration and phonation change following Lax Vox voice therapy for patients with PD and this finding suggested that Lax Vox voice therapy also can be an effective treatment option for improvig their ability to communicate and voice-related difficulties in daily life in Parkinson''s disease patients.