Acoustic properties of vowel production in Mandarin-speaking patients with post-stroke dysarthria

Abstract

This study investigated the acoustic features of vowel production in Mandarin-speaking patients with post-stroke dysarthria (PSD). The subjects included 31 native Mandarin-speaking patients with PSD (age: 25–83 years old) and 38 neurologically normal adults in a similar age range (age: 21–76 years old). Each subject was recorded producing a list of Mandarin monosyllables that included six monophthong vowels (i.e., /a, i, u, ɤ, y, o/) embedded in the /CV/ context. The patients’ speech samples were evaluated by two native Mandarin speakers. The evaluation scores were then used to classify all patients into two levels of severity: mild or moderate-to-severe. Formants (F1 and F2) were extracted from each vowel token. Results showed that all vowel categories in the patients with PSD were produced with more variability than in the healthy speakers. Great overlaps between vowel categories and reduced vowel space were observed in the patients. The magnitude of the vowel dispersion and overlap between vowel categories increased as a function of the severity of the disorder. The deviations of the vowel acoustic features in the patients in comparison to the healthy speakers may provide guidance for clinical rehabilitation to improve the speech intelligibility of patients with PSD.

A Systematic Review of Measures of Dysarthria Severity in Stroke Patients

“…In particular, patients with a greater F2 slope tend to have higher intelligibility scores. Greater F1 variability is also predictive of speech intelligibility in dysarthric speakers 58 …”

“…Acoustic parameters and intelligibility tests could be used to develop a quantitative metric of severity in speech disorders related to several neurological disorders 56,57 . These parameters could guide rehabilitation to improve the speech intelligibility, help to predict the prognosis, and determine the side of the lesion 58 . Unilateral hemispheric stroke is associated with voice disorders, especially those involving frequency perturbation parameters, amplitude parameters, and fundamental frequency variability (vF0) 9 …”

“…It is necessary to examine the formants in the assessment of vowel in dysarthric subjects after a stroke 58 . The intelligibility scale is associated with formants.…”

“…The intelligibility scale is associated with formants. Dysarthria usually causes unstable vowel formant patterns, reduces F2 slopes, 59‐61 and results in abnormal values of F1 and F2 for the vowels /i/ and /u/ 58 . The F2 slope is correlated with speech intelligibility in dysarthria patients with various types of diseases, including stroke 60‐62 .…”

Diagnosing Dysarthria with Long Short-Term Memory Networks

“…They all had puretone thresholds at 500, 1000, and 2000 Hz of ≤ 25 dB HL in at least one ear with no reported hearing or speech disorders. More details about the demographical information of the participants and the acoustic properties of the speech samples can be found in [6]. Informed consent was obtained from all participants.…”