Size of Velopharygeal Opening and Nasality Measurements from Acoustic Features

Abstract

Previous research has explored the relationship between nasality measures obtained from acoustic signals [Chen 1997, JASA 102] and direct measurements such as nasal airflow, highlighting promising outcomes. Carignan [2021, JASA 149; 2023, LabPhon 14] reported that nasality measurements from acoustic features (NAF) using machine learning algorithms like PCA regression and XGBoost highly correlate with airflow data. However, it remains unclear how well acoustic measurements align with the actual size of the velopharyngeal opening (VPO). To address this, the current study examines the correspondence between acoustic measurements of nasality and the size of the VPO. We conducted an investigation using running speech samples produced by 4 Canadian English speakers, obtained from the Université Laval X-ray videofluorography database [Munhall et al. 1995, JASA 98]. Using ImageJ software, we tracked the opening and closing movements of the VPO in both nasal and oral segments. Subsequently, we employed the NAF method [Carignan 2023, LabPhon 14] to measure the degree of nasality in the speech samples. We compared the NAF measurements of nasality with the data obtained from the VPO tracking to assess the degree of correlation between the two measures. The results of our study indicate a positive alignment between nasality measurements derived from acoustic signals and the VPO data. This finding suggests that NAF measurements can be a decent predictor of the actual size of the VPO in nasal speech vs. oral speech segments, indicating a positive relationship between NAF, VPO, and nasal airflow. These results have implications for our understanding of nasality production and contribute to the growing body of research on the relationship between acoustic measurements and physiological aspects of speech production. [Work supported by NIH and NSERC.]