Effect of bilateral stimulation of the subthalamic nucleus in parkinsonian voice
Gentil, M., Chauvin, P., Pinto, S., Pollak, P., & Benabid, A.L . (2001) Effect of bilateral stimulation of the subthalamic nucleus in parkinsonian voice , 78, 233-240
This study examined the acoustic parameters of speech (including phonemic duration, fundamental frequency, and relative intensity) in various speech tasks in 26 PD patients while on or off stimulation. The patients’ speech was moderately impaired when assessed without medication and without stimulation. The results showed that while on stimulation, patients were able to lengthen their maximal phonation time (the elapsed time of the speech sounds made by the vibration of the vocal cords) of sustained vowels and reduced their pauses in phrase repetitions during a 30 second speech sample. Post surgery in an "on state", patients varied the pitch of their voice, and their speech sounded more normal and natural.