Acoustic and Perceptual Consequences of Clear and Loud Speech

Abstract

Objective: Several issues concerning F2 slope in dysarthria were addressed by obtaining speech acoustic measures and judgments of intelligibility for sentences produced in Habitual, Clear and Loud conditions by speakers with Parkinson's disease (PD) and healthy controls. Patients and Methods: Acoustic measures of average and maximum F2 slope for diphthongs, duration and intensity were obtained. Listeners judged intelligibility using a visual analog scale. Differences in measures among groups and conditions as well as relationships among measures were examined. Results: Average and maximum F2 slope metrics were strongly correlated, but only average F2 slope consistently differed among groups and conditions, with shallower slopes for the PD group and steeper slopes for Clear speech versus Habitual and Loud. Clear and Loud speech were also characterized by lengthened durations, increased intensity and improved intelligibility versus Habitual. F2 slope and intensity were unrelated, and F2 slope was a significant predictor of intelligibility. Conclusion: Average diphthong F2 slope was more sensitive than maximum F2 slope to articulatory mechanism involvement in mild dysarthria in PD. F2 slope holds promise as an objective measure of treatment-related changes in the articulatory mechanism for therapeutic techniques that focus on articulation.

Speech Intelligibility in Dysarthrias: Influence of Utterance Length

“…According to the study by De Bodt et al [6], different dimensions of speech, such as vocal quality, nasality, articulation, and prosody, may explain measures of intelligibility obtained from a speaker, and articulation contributes the most. These data are strengthened by findings from studies using acoustic measures of articulation that showed a correlation with intelligibility measures [13,38]. As each neurologic disease can produce different impairments in all sensorimotor bases of speech, including articulation, it is possible that the effect of utterance length on the intelligibility of target words varies according to the type of dysarthria.…”

“…Other studies have already pointed out that the condition of speech production, such as speech at low speed, loud speech, and clear speech, may contribute to increased speech intelligibility [13][14][15]. Despite the results found in these studies, Tjaden and Weismer [16], who investigated the effect of speed on acoustic measurements of speech production, indicated the existence of variation between speakers.…”

Vocalic transitions as markers of speech acoustic changes with STN-DBS in Parkinson’s Disease

“…The slope of this precisely delimited transition was finally measured by dividing the overall frequency change (transition extent) by the transition duration. This same procedure has been used in past studies investigating diphthong slopes in dysarthria (Tjaden, Richards, Kuo, Wilding, & Sussman, 2013). …”

Relationship between acoustic measures and judgments of intelligibility in Parkinson’s disease: A within-speaker approach

“…Recently, Kim et al (2011b) investigated the relationship between various acoustic measures, including F2 slope and speech intelligibility in speakers varying in dysarthria severity. Results indicated that shallower F2 slopes were associated with poorer speech intelligibility (see also Kim, Weismer, Kent, & Duffy, 2009; Tjaden, Richards, Kuo, Wilding, & Sussman, 2013; Yunusova et al, 2012). …”