in this paper the distributions of sound pressure in the oral cavity are studied based on acoustic measurement which was performed by inserting a probe microphone into the oral cavity during steady-state utterance of the Japanese vowels /a/ and /o/. The actual sound pressure levels and the relative distributions of sound pressure on the midsagittal plane for these vowels are presented. By using the results of our previous measurement using a plaster replica of the oral cavity, 2-dimensional sound pressure distribution for /a/, which approximates the measured midsagittal sound pressure curve, is also computed. The computed pressure distribution agrees with the measured data to within 2 dB differences when an average asymptotic decay of 6 dB/oct is given.