Extended Study on the Use of Vocal Tract Variables to Quantify Neuromotor Coordination in Depression.

Changes in speech production that occur as a result of psychomotor slowing, a key feature of Major Depressive Disorder (MDD), are used to non-invasively diagnose MDD. In previous work using data from seven subjects, we showed that using speech-inverted vocal tract variables (TVs) as a direct measure of articulation to quantify changes in the way speech is produced when depressed relative to being not depressed outperforms formant information as a proxy for articulatory information. In this paper, we made significant extensions by using more subjects, taking into account more eigenvalue features and incorporating TVs related to (1) place of articulation and (2) the glottal source. These additions result in a significant improvement in accuracy, particularly for free speech. As a baseline, we perform a similar analysis using higher-dimensional Mel Frequency Cepstral Coefficients (MFCCs).