The effects of deep brain stimulation on conversational and repeated speech

The effects of the DBS on speech remain controversial. This approach used intelligibility by listeners and acoustic parameters as measures of conversation and repeated speech. Persons with DBS-STN provided conversational speech samples and then repeated portions of their conversation in both on and off stimulation. Excerpts were arranged for a listening protocol adjusted for the Parkinsonian hypophonia. Dependent measures were intelligibility and difficulty ratings by 30 healthy listeners and acoustic measures of voice. Fewer words were correctly transcribed from conversation compared to repetition [F(1,29) = 14.06; p = 0.001]. Similarly, intelligibility for STN-DBS on worse than off [F(1,29) = 9.462; p = 0.005]. More words were correctly transcribed from repetition than from conversation with STN-DBS on [t(29) = -2.342; p = 0.026] and off [t(29) = -3.619; p = 0.001]. Comparisons of conversation versus repetition and DBS state revealed significant effects of both task and DBS on intelligibility. Repetitio...