Changes in Vowel Articulation with Subthalamic Nucleus Deep Brain Stimulation in Dysarthric Speakers with Parkinson’s Disease

Table 4

Formant frequencies, acoustic vowel space, formant centralization ratio, and vowel duration at OFF- and ON-stimulation: means (standard deviations), and values.

	/i/		/u/		/a/		Acoustic vowel space (Hz^2)	Formant centralization ratio	Vowel duration (ms)
	(Hz)	(Hz)	(Hz)	(Hz)	(Hz)	(Hz)
OFF-stimulation	311.5	2233.1	329.2	1186.6	583.3	1736.3	152036	1.240	130.2
	(54.4)	(219.0)	(66.6)	(283.1)	(127.6)	(263.5)	(14251)	(0.035)	(8.8)
ON-stimulation	307.6	2345.7	328.5	1077.0	680.1	1753.0	227759	1.142	138.4
	(45.1)	(264.4)	(61.3)	(250.1)	(91.1)	(268.0)	(17905)	(0.031)	(10.5)
						Change	+75723	−0.098	+8.2
							(11504)	(0.20)	(5.1)
							43.327	24.482	2.665
							<0.000*	<0.01*	>0.05

*Significant effect.