Thea Knowles


Thea Knowles.

Thea Knowles


Thea Knowles


Current Work

My research focuses on describing the acoustic-phonetic characteristics of dysarthria, a group of motor speech disorders. In particular, I am interested in how changes in the acoustic speech signal modulate speech intelligibility, that is, how understandable one’s speech is to a typical listener. Informed by my background in linguistics and speech acoustics, my research can broadly be categorized into three themes:

1. Understanding variable and adverse treatment effects on speech

2. Acoustic distinctiveness and its role in speech intelligibility

3. The use of technology for speech measurement and treatment

While much of my research has focused on hypokinetic dysarthria, a motor speech disorder associated with Parkinson’s disease, I am also interested in the differential speech processes in younger and older healthy adults, as well as individuals with other neurological speech disorders.


- PhD, Western University, 2019, Health & Rehabilitation Sciences (Speech and Language Sciences)

- MClSc-SLP, Western University, 2019, Communication Sciences & Disorders (combined MClSc/PhD degree program)

- BA Honours, McGill University, 2012, Linguistics


CDS 288, Anatomy & Physiology of the Speech Mechanism

Recent Publications

  • Sonderegger, M., Stuart-Smith, J., Macdonald, R., Knowles, T., & Rathcke, T. (in press). Structured heterogeneity in Scottish stops over the twentieth century. To appear in Language.
  • Abeyesekera, A., Adams, S., Mancinelli, C., Knowles, T., Gilmore, G., Delrobaei, M., Jog, M. (2019). Effects of deep brain stimulation of the subthalamic nucleus settings on voice quality, intensity, and prosody in Parkinson’s disease: preliminary evidence for speech optimization. Canadian Journal of Neurological Sciences, 46(3), 287-294. doi: 10.1017/cjn.2019.16
  • Knowles, T., Clayards, M., & Sonderegger, M. (2018). Examining factors influencing the viability of automatic acoustic analysis of child speech. Journal of Speech, Language, and Hearing Research, 61(10), 2487-2501. doi: 10.1044/2018 JSLHR-S-17-0275.
  • Knowles, T., Adams, S., Abeyesekera, A., Mancinelli, C., Gilmore, G., & Jog, M. (2018). Deep brain stimulation of the subthalamic nucleus parameter optimization for vowel acoustics and speech intelligibility in Parkinson’s disease. Journal of Speech, Language, and Hearing Research, 61(3), 510-524. doi: 10.1044/2017 JSLHR-S-17-0157.
  •  Cushnie-Sparrow, D., Adams, S.G., Knowles, T., Leszcz, T.M., Jog, M. (2016). Effects of multitalker noise on the acoustics of voiceless stop consonants in Parkinson’s disease. Western Papers in Linguistics.
  • Knowles, T., Clayards, M., Sonderegger, M., Wagner, M., Nadig, A., & Onishi, K. (2015). Automatic forced alignment on child speech: Directions for improvement. Proceedings of Meetings on Acoustics. doi: 10.1121/2.0000125
  • Clayards, M. & Knowles, T. (2015). Prominence enhances voicelessness and not place distinction in English voiceless sibilants. Proceedings of the 18th International Congress of Phonetic Sciences. Glasgow, UK: University of Glasgow.