Development of medical techniques with magnetic resonance imaging (MRI) has increased our knowledge of voice production mechanisms in speech and singing. Our experience with high-resolution imaging techniques has also provided us new insights into physiological and acoustic aspects of voice production process. Physiologically, the larynx is under the control of the surrounding motor apparatus, and changes in voice fundamental frequency is dependent not only on the internal laryngeal functions but also on the external mechanisms influencing on the larynx mediated by the supra- and infra-hyoid muscles. This view was supported by observations with electromyography and has been revealed in depth with laryngeal MRI. Acoustically, the cavities of the hypopharynx (laryngeal cavity and pyriform fossa) give rise to characteristic spectral patterns that signal voice quality and individual characteristics at the frequencies above 2.5 kHz. The role of these cavities apparently differs from that of the main vocal tract for vowel production. Those discoveries derived mainly from male data, however, do not always agree with female data in detail. With this question in mind, our recent studies to search into singing formant in soprano voice will be discussed in relation to the roles of the hyoid-larynx complex for physiology and the hypo-pharyngeal cavities for acoustics.