Arian Shamei

PhD Candidate – Linguistics, University of British Columbia, Vancouver, Canada

Speech motor control – Neural imaging – Detection of clinical states

Arian is the founder of the Speech and Neurological Disease (SaND) group, a component of the ISRL which investigates the effects of neurological disease (such as Alzheimer’s and Parkinson’s disease) on speech motor control, and the development of machine learning models for clinical detection

Selected publications

Cortical control of posture in fine motor skills: Evidence from inter-utterance rest position
Easthope, E., Shamei, A., Liu, Y., Gick, B., & Fels, S. (2023). Cortical control of posture in fine motor skills: evidence from inter-utterance rest position. Frontiers in Human Neuroscience, 17.

The vocal tract continuously employs tonic muscle activity in the maintenance of postural configurations. Gamma-band activity in the sensorimotor cortex underlies transient movements during speech production, yet little is known about the neural control of postural states in the vocal tract. Simultaneously, there is evidence that sensorimotor beta-band activations contribute to a system of inhibition and state maintenance that is integral to postural control in the body. Here we use electrocorticography to assess the contribution of sensorimotor beta-band activity during speech articulation and postural maintenance, and demonstrate that beta-band activity corresponds to the inhibition of discrete speech movements and the maintenance of tonic postural states in the vocal tract. Our findings identify consistencies between the neural control of posture in speech and what is previously reported in gross motor contexts, providing support for a unified theory of postural control across gross and fine motor skills.

Reduction of vowel space in Alzheimer’s Disease
Shamei, A., Liu, Y., & Gick, B. (2023). Reduction of vowel space in Alzheimer’s disease. JASA Express Letters, 3(3), 035202.

Reduced vowel space area (VSA) is a known effect of neurodegenerative diseases such as Parkinson’s disease (PD). Using large publicly available corpuses, two experiments were conducted comparing the vowel space of speakers with and without Alzheimer’s disease (AD) during spontaneous and read speech. First, a comparison of vowel distance found reduced distance in AD for English spontaneous speech, but not Spanish read speech. Findings were then verified using an unsupervised learning approach to quantify VSA through cluster center detection. These results corroborate observations for PD that VSA reduction is task-dependent, but further experiments are necessary to quantify the effect of language

Automated detection of cannabis intoxication from speech
Shamei, A., Sullivan, P. R., Liu, Y., Abdul-Mageed, M., & Gick, B. (2021). Automated detection of cannabis intoxication from speech. Canadian Acoustics, 49(2).

Machine learning can reliably distinguish a variety of mental and physical states based on acoustic alterations in the speech stream. Recent acoustic research found that cannabis intoxication results in significant differences in several acoustic correlates. Encouraged by these observations, we report models aimed at detecting cannabis intoxication from human speech. We exploit mel spectrograms from sober and intoxicated productions of sustained vowels, to train models under various gender-nuanced conditions (i.e., male-only, female-only, gender-agnostic) using convolutional neural networks (CNNs). In speaker-independent cross-validation, we report highly effective models (avg macro F 1 – females : 68.6%, males : 67.9%).

Anti-gravity posture in speech motor control
Shamei, A., Soskuthy, M., Stavness, I., & Gick, B. (2022, Preprint). Anti-gravity posture in speech motor control. https://doi.org/10.31234/osf.io/5jrcp

Understanding the role of anti-gravity behaviour in fine motor control is crucial to achieving a unified theory of motor control. We compare speech from astronauts before and immediately after microgravity exposure to evaluate the role of anti-gravity posture during fine motor skills. Here we show a generalized lowering of vowel space after space travel, which suggests a generalized postural shift of the articulators. Biomechanical modelling of gravitational effects on the vocal tract supports this analysis – the jaw and tongue are pulled down in 1g, but movement trajectories of the tongue are otherwise unaffected. These results demonstrate the role of anti-gravity posture in fine motor behaviour and provide a basis for the unification of motor control models across domains.

F0-related head movement in blind versus sighted speakers 
Liu, Y., Shamei, A., Chow, U. Y., Soo, R., Pineda Mora, G., de Boer, G., & Gick, B. (2020). F 0-related head movement in blind versus sighted speakers. The Journal of the Acoustical Society of America, 148(2), EL190-EL194.

This study investigated the relationship between head movement and fundamental frequency (F0) during speech by comparing continuous speech of congenitally blind and sighted speakers from YouTube videos. Positive correlations were found between F0 (measured in semitones) and vertical head movement for both speaker groups, with a stronger correlation for blind speakers. In addition, larger head movements and larger head movement per semitone ratios were observed for sighted speakers. These results suggest that physiological processes may account for part of the F0-related head movement and that sighted speakers use the visual modality to communicate F0 information through augmented head movement