A Preliminary Report on Disordered Speech with Deep Brain Stimulation in Individuals with Parkinson's Disease

Table 3

Vocal perturbation for vowel phonation with and without stimulation.

Participant	Variable	Stimulation on	Stimulation off
F1	Jitter (%)	7.69	2.35
	Shimmer (%)	5.69	5.79
	HNR (dB)	10.12	19.46
M4	Jitter (%)	2.22	1.17
	Shimmer (%)	16.57	8.52
	HNR (dB)	14.01	18.06
M5	Jitter (%)	0.43	0.44
	Shimmer (%)	1.24	5.15
	HNR (dB)	24.44	21.12
M8	Jitter (%)	0.22	0.27
	Shimmer (%)	0.80	0.77
	HNR (dB)	27.33	31.49
M9	Jitter (%)	0.58	0.62
	Shimmer (%)	5.60	6.66
	HNR (dB)	20.33	19.23
M10	Jitter (%)	1.53	2.59
	Shimmer (%)	8.36	12.78
	HNR (dB)	16.57	13.37

HNR: harmonics-to-noise ratio; higher values reflect better performance. Higher jitter and shimmer percentages are reflective of greater perturbation or vocal unsteadiness.