Previous studies confirmed that during whispering the glottis is kept open to prevent vocal fold vibration and the supraglottal structures are constricted. However, there has been no study exploring the exact contour of the laryngeal lumen in the frontal dimension during the production of whispering. In order to further elucidate the nature of the laryngeal adjustments regarding the contour of the laryngeal lumen in whispering, and the role of supraglottal constriction in particular, we conducted a physiological study using magnetic resonance imaging. According to the results, the supraglottal structures were not only constricted but also shifted downward, attaching to the vocal fold to prevent vocal fold vibration completely during whispering. The results suggested the underlying mechanism of suppression of vocal fold vibration during the production of whispering.