It is reported that patients who have undergone dental surgery of implanting prosthetic teeth often suffer from pronunciation disorders. In reference to the past studies which report a correspondence of the peak in a frequency spectrum between the fricative sound and the vibration of anterior teeth, it was hypothesized that the postoperative pronunciation disorders were attributable to a change in the vibration mode of anteriorly-implanted prosthetic teeth that have different elastic natures from natural teeth. The present study was designed to investigate effects of elastic properties of anteriorly-positioned prosthetic teeth on characteristics of its vibration and the emitted-sound. The flow channel was fabricated such that it morphologically simplified an oral cavity when sibilant/s/, one of the fricatives, is pronounced. An obstacle wall that is a model of anteriorly-positioned prosthetic teeth was made of four materials having different elasticity. The results demonstrated that the obstacle wall of different elasticity resulted in different modes of the vibration. However, the frequency spectrum of the emitted sound appeared to be almost the same irrespective of the elastic property of the teeth. Those results indicated less contributions of the teeth vibration to acoustic nature of the emitted sound, thereby suggesting that the postoperative pronunciation disorders is not due to a change in the vibration mode of prosthetic teeth at the anterior position.