Speech timing measures of severity, psychomotor retardation, and agitation in endogenously depressed patients.

Mean duration and frequency of pauses within speech, pauses between speakers, and vocal activity were measured in 28 endogenous depressive during a psychiatric interview. A factor analysis on these variables revealed two factors accounting for 50% and 24% of the variance, respectively. Factor 1 could be interpreted as a pause factor. The mean durations of both types of pauses had high negative loadings, whereas the frequency of vocal activity, simultaneous speech, and pauses, and the mean duration of vocal activity had high positive loadings on this factor. The degree of retardation (a measure for slowed mental and physical activity) also was related to this factor (r = -0.67, p less than 0.001), whereas the relation between the severity of depression and this factor could only be established under certain conditions. The second factor was interpreted as a fragmentation of speech factor. The frequency of switching pauses (between speakers) and of vocal activity had high positive loadings, and the mean duration of vocal activity had a high negative loading. No clear relationships could be demonstrated between the degree of agitation (a measure for mental and physical overactivity) and speech and pause variables.