抄録
In recent years, with the never ending progress in technology related to audio visual equipments and PC, etc., there is an increasing trends of using the reproduction sound of contents such as music and speech even for household purposes. Since all the phenomena occurring in nature need to be considered in relative frame of reference, a pleasant and enjoyable sound to the listener may appear as a noise to the people (non-listener) around the owner of sound player. Therefore, the aim of the present work is to develop a sound field control technology which confined the sound field to the listener only. In this regard, the author first focused his attention to the relation between the vibration area of the speaker and the attenuation ratio. Based on that is proposed a method to change attenuation ratio so that sound pressure level remain same in the near field, but its level reduces in the far field. In this technique, the primary and secondary sound source of different vibration area is interacted by using antrphase of the primary sound source. Based on the experiment and theoretical estimation the performance of the present technique is verified. In addition, the present performance in a real environment is estimated.
