Voice as the sound of the psyche: Changes in prosodic characteristics in depressive patients in long-term therapy

BACKGROUND Voice is individual and therefore several studies consider voice as a biomarker of health. Focusing on the change of voice parameters of depressed patients can provide an additional, objective measurement of the patient’s individual progress during psychotherapy. This retrospective study is focused on the analysis of voice parameters, specifically prosodic parameters, gathered from sessions and real-world data out of the Munich psychotherapy study (MPS). AIM To investigate the prosodic parameters of patients with depression, their change over a long-term therapy and correlate them with Beck depression inventory (BDI) data. The analysis on the prosodic parameters aims to find, if and to what extent, a change in the patient’s voice can be discovered and identified. This data is then correlated with already available BDI data of each individual patient. The hypothesis is that voice expression is impacted by depression and changes with the state of depression. METHODS We performed a retrospective investigation of n = 25 patients, who originally participated in the MPS, and their change in prosodic parameters. An analysis of the mean fundamental frequency fo and its standard deviation was performed on six psychotherapy sessions per patient, divided into three sessions at the beginning of the therapy and three sessions at the end of the therapy. The technical analyses on the voice part have been conducted with Praat, a phonetic analysis software developed at the University of Amsterdam. RESULTS The mean fundamental frequency was fo ,mean = 183.1 Hz at the beginning and fo ,mean = 187.8 Hz at the end, in a compounded group of all patients (men and women). The average BDI of all patients at the beginning was BDImean = 29.96 and BDImean = 9.6 at the end. A positive influence of psychotherapy can be seen in the majority of patients not only in a reduced BDI rating, but also in an increased baseline frequency. CONCLUSION With regard to the clinical picture of depression, its recognition and constant monitoring during therapy, it is important to exhaust all possibilities and examine additional relevant data. Prosodic characteristics can make a contribution here for various reasons. On the one hand, a person acts unconsciously via and through their voice and emotional states become detectable. On the other hand, voice can be represented in objective parameters and is therefore suitable for analyzing individual characteristics and changes. Dealing with the topic from the perspective of psychotherapy therefore seems unavoidable, as an additional component is included in the holistic view of the person.