Effect of stress on fundamental frequency of the voice

Abstract

The effect of stress on the fundamental frequency of voice was assessed in two studies with 16 and 15 subjects, respectively. In each study, student nurses either saw a pleasant nature film and had to give truthful reports about it and their feelings toward it to an interviewer (baseline situation), while in the stress situation they saw an extremely unpleasant medical film and had to deceive the interviewer about their feelings. Subjects' answers to seven interviewer questions were separately analyzed for fundamental frequency (using digital F0 extraction procedures). A methodological analysis showed that mean F0 for very short samples (20 sec) correlates very highly with mean F0 for the total interview. In both studies F0 was significantly elevated in the stress condition (mean difference +9.0 Hz, combined p = 0.0003). For 25.5% of the subjects a reversal was observed. A positive correlation between extent of F0 elevation under stress and low scoring on the CPI Achievement via Independence scale (partialing out Achievement via Conformance, r = 0.65, p < 0.01, N = 31) suggests that F0 response to stress may be determined by individual coping strategies. Mean F0 levels for different answers significantly differentiated between different stages of the interview, presumably related to changing transitory stress levels.