Table 3.

Summary of published findings related to lexical segmentation of dysarthric speech from the Motor Speech Disorders Laboratory at Arizona State University

Speaker population	Analysis type(s)	Findings	Publication
Hypokinetic	LBE analysis Acoustic measures of syllable strength	All listeners used syllabic strength for lexical segmentation decisions Strategy was less effective for severely impaired speech and reduced strength cues	Liss et al. [68]
Hypokinetic Ataxic	LBE analysis Acoustic measures of syllable strength	Replicated hypokinetic findings from our 1998 study [68] Ataxic dysarthria did not elicit predicted LBE patterns Concluded prosodic disturbance in ataxic dysarthria renders metrical segmentation difficult	Liss et al. [72]
Hypokinetic Ataxic	LBE analysis	Replicated previous hypokinetic and ataxic findings from Liss et al. [68, 72] Brief familiarization benefited all listeners Greater dysarthria-specific than dysarthria-general benefits, but overall no change in LBE patterns Concluded that ‘learning’ associated with familiarization may be at the segmental level	Liss et al. [72]
Hypokinetic Ataxic	Word substitution analysis	In a reanalysis of Liss et al.’s [72] data, word substitutions were segmentally closer to the targets in transcriptions of ataxic as compared with hypokinetic dysarthric speech This offers evidence that familiarization may be learning at the segmental level	Spitzer et al. [93]
Resynthesized speech	LBE analysis	Healthy control speech resynthesized to approximate dysarthria-like prosodic patterns Conditions of flattened F0 and of reduced second formant toward a schwa in full vowels resulted in the greatest impediment to implementing a metrical segmentation strategy Findings did not align completely with expectations for duration-cue reductions and ataxic speech predictions	Spitzer et al. [63]
Healthy control Hypokinetic Ataxic Hyperkinetic Mixed spastic-flaccid	Temporally based rhythm metrics DFA	DFAs distinguished rhythm metrics for healthy control speech from those of dysarthric speech Rhythm metrics reliably classified dysarthrias into their categories with good accuracy	Liss et al. [6]
Healthy control Hypokinetic Ataxic Hyperkinetic Mixed spastic-flaccid	EMS DFA	EMS, an automated spectral analysis of the low-rate amplitude modulations of the envelope for the entire speech signal and within select frequency bands, performed as well as the hand-measured vocalic and intervocalic interval durations employed in Liss et al. [6]	Liss et al. [15]
Mixed spastic-flaccid	LBE analysis	Data show evidence for cue use differences among better and poorer listeners	Choe et al. [71]

DFA = Discriminant function analysis; EMS = envelope modulation spectrum.