In recent years physiological indexes of emotion have made their comeback as indicators of prejudice, but vocal measures have lagged behind. The aim of this study is to examine the vocal changes in arousal and intimacy that occur in real-life interactions with a woman who wears the Islamic headscarf or hijab. The study is based on a field experiment performed in the Paris metro. Assuming that vocal behavior serves an expressive function, the hijab is expected to provoke higher arousal and lower intimacy. Assuming that vocal behavior can alternatively function to manage impressions, and in view of observed gender differences, the hijab is expected to elicit lower arousal and higher intimacy among women but to have the opposite effect among men. The data indicates that in response to the hijab arousal decreases among women but increases among men, while intimacy decreases both among women and men. The historically most reliable acoustic measures of arousal, in particular the fundamental frequency, conform to the expectations, arguing for the internal validity of this naturalistic experiment.