Research Group 'Psychiatric Genetics', Head: Prof. Dr. Hans H. Stassen

Department of Psychiatry, Psychotherapy and Psychosomatics

Psychiatric Hospital, University of Zurich


Speech Characteristics in Schizophrenia, Bipolar Illness and Depression

Speech Dysfunctions

Speech dysfunction, such as slow, delayed or monotonous speech, the inability to express a normal range of affective responses, or psychomotor retardation, are prominent features of patients suffering from severe depression or schizophrenia. Accordingly, clinicians routinely monitor speaking behavior and voice sound characteristics in those patients for diagnostic purposes and as indicator of clinical change. Current developments in computerized approaches to speech analysis give rise to optimistic expectations regarding routine applications of the speech analysis method when addressing the time course of recovery from depression, the time point of onset of action under antidepressant treatment, the prospective identification of patients with long-persisting affective deficits, and the biological validation of the negative-positive model of schizophrenia.

Principal Goals

Based on psychopathology assessments and speech recordings on 491 patients suffering from major depression, bipolar illness and schizophrenia, this project aimed at quantifying affect disturbances, psychomotor retardation and various negative-positive aspects of schizophrenia through a computerized analysis of speaking behavior and voice sound characteristics. The results obtained from our previous normative studies were used as reference in order to distinguish between "natural" fluctuations and "significant" changes. The large sample sizes available for this investigation enabled a random-splitting approach so that the reproducibility of results could be verified.

Speech Recordings

Specifically, we focused our interest on the following questions: (1) Do acoustic variables discriminate between "depressive" affect and "negative" affect? (2) Do acoustic variables prospectively discriminate between patients who suffer from long-persisting cognitive deficits that are still present when the acute symptomatology has significantly improved, and patients who exhibit a prompt onset of improvement with respect to acute symptomatology, affect deficits and negative symptoms? (3) Can acoustic variables be used to explain the severity of the negative and positive components of schizophrenia?


Acoustic variable were found to clearly discriminate between patients and healthy controls. Specifically, a configuration of 6 acoustic variables predicted the severity of the negative syndromes. Speaking behavior and voice sound characteristics may be distinct aspects of severe affective and schizophrenic disorders which persist in a subgroup of patients over quite a long time even when acute psychopathology symptoms have significantly improved. There exists considerable inter-individual variation as to how cognitive impairment affects the patients' speech and voice sound characteristics.


Braun S, Annovazzi C, Botella C, Bridler B, Camussi E, Delfino JP, Mohr C, Moragrega I, Papagno C, Pisoni A, Soler C, Seifritz E, Stassen HH: Assessing Chronic Stress, Coping Skills and Mood Disorders through Speech Analysis. A Self-Assessment "Voice App" for Laptops, Tablets, and Smartphones. Psychopathology 2016; 49(6): 406-419 [get the article]
Delfino JP, Barragán E, Botella C, Braun S, Bridler R, Camussi E, Chafrat V, Lott P, Mohr C, Moragrega I, Papagno C, Sanchez S, Seifritz E, Soler C, Stassen HH: Quantifying Insufficient Coping Behavior under Chronic Stress. A cross-cultural study of 1,303 students from Italy, Spain, and Argentina. Psychopathology 2015; 48: 230-239
Braun S, Botella C, Bridler R, Chmetz F, Delfino JP, Herzig D, Kluckner VJ, Mohr C, Moragrega I, Schrag Y, Seifritz E, Soler C, Stassen HH: Affective State and Voice: Cross-Cultural Assessment of Speaking Behavior and Voice Sound Characteristics. A Normative Multi-Center Study of 577+36 Healthy Subjects. Psychopathology 2014; 47(5): 327-340
Mohr C, Braun S, Bridler R, Chmetz F, Delfino JP, Kluckner VJ, Lott P, Schrag Y, Seifritz E, Stassen HH: Insufficient Coping Behavior under Chronic Stress and Vulnerability to Psychiatric Disorders. Psychopathology 2014; 47: 235-243
Stassen HH, Delfino JP, Kluckner VJ, Lott P, Mohr C: Vulnerabilität und psychische Erkrankung. Swiss Archives of Neurology and Psychiatry 2014; 165(5): 152-157
Stassen HH (2004) Veränderungen der Sprechmotorik. In: T.Jahn (ed) Bewegungsstörungen bei psychischen Erkrankungen. Springer Heidelberg: 107-125
Stassen HH, Angst J (2002) Wirkung und Wirkungseintritt in der Antidepressiva-Behandlung. In: Böker H and Hell D (eds) Therapie der affektiven Störungen. Stuttgart und New York: Schattauer 141-165
Lott PR, Guggenbühl S, Schneeberger A, Pulver AE, Stassen HH (2002) Linguistic analysis of the speech output of schizophrenic, bipolar, and depressive patients. Psychopathology 35(4): 220-227
Püschel J., Stassen HH, Bomben G, Scharfetter C and Hell D (1998) Speaking behavior and voice sound characteristics in acute schizophrenia. J. Psychiatric Research 32, 89-97
Stassen HH, Kuny S, Hell D (1998) The speech analysis approach to determining onset of improvement under antidepressants. Eur. Neuropsychopharmacology 8(4), 303-310
Kuny S, Stassen HH, Hell D (1997) Kognitive Beeinträchtigungen in der Depression. Schweiz Arch Neurol Psychiatrie 150,3: 18-25
Stassen HH (1995) Affekt und Sprache. Stimm- und Sprachanalysen bei Gesunden, depressiven und schizophrenen Patienten. Monographien aus dem Gesamtgebiete der Psychiatrie, Bd. 79. Berlin, Heidelberg: Springer
Stassen HH, Albers M, Püschel J, Scharfetter C, Tewesmeier M, Woggon B (1995) Speaking behavior and voice sound characteristics associated with negative schizophrenia. J Psychiat Res. 29, 277-296
Kuny S, Stassen HH (1993) Speaking behavior and voice sound characteristics in depressive patients during recovery. J Psychiat Res. 27, 289-307
overtone distribution
Voice sound characteristics ("timbre") of a female speaker as quantified through spectral analyses. Spectral intensities are plotted along the y-axis on log-proportional scales and as a function of frequency (x-axis: 7 octaves covering the frequency range of 64-8192Hz).
Mean vocal pitch in females lies 1 octave above that of male speakers. Distribution and intensity of overtones as produced with vowels "a", "e", "i", "o", "u" form characteristic patterns, which display large inter-individual variation, thus enabling a computerized recognition of persons through their spectral voice patterns.
Please note: Depression significantly reduces the dynamic expressiveness of human voices, thus greatly reducing inter-individual differences. As a direct consequence, the patients' voices become more similar to each other ("depressive voice"). Voices regain their distinct individuality during recovery.
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