Inter-speaker acoustic differences of sustained vowels at varied dysarthria severities for amyotrophic lateral sclerosis

We study inter-speaker acoustic differences during sustained vowel utterances at varied severities of Amyotrophic Lateral Sclerosis-induced dysarthria. Among source attributes, jitter and standard deviation of fundamental frequency exhibit enhanced inter-speaker differences among patients than healthy controls (HCs) at all severity levels. Though inter-speaker differences in vocal tract filter attributes at most severity levels are higher than those among HCs for close vowels /i/ and /u/, these are comparable with or lower than those among HCs for the relatively more open vowels /a/ and /o/. The differences typically increase with severity except for a few parameters for /a/ and /i/.