Exploration of Metrics for Quantifying Formant Space: Implications for Clinical Assessment of Parkinson Disease

Purpose Speakers with Parkinson disease (PD) often exhibit hypokinetic dysarthria, which affects speech articulation. Vowel space metrics based on formant frequencies have been used to examine vowel articulation in speakers with PD. Although data from a number of studies suggest that speakers with PD exhibit smaller acoustic vowel space areas than control speakers, a handful of studies did not observe differences in vowel space area between speakers with and without PD. One potential factor explaining the inconsistent performance of traditional vowel space metrics is that these point-based metrics undersample the formant space to adequately capture between-groups and within-group differences in articulation. This article discusses recent advances in vowel space assessment that augment traditional vowel space metrics by examining the distribution of the entire formant frequency trace. Conclusion A general approach to obtaining these metrics is discussed along with clinical implications for vowel space assessment in speakers with PD.