Personal sound field manipulation in the wearable audio device

A study of personal sound field manipulation is getting more attention recently as wireless personal audio devices become popular. Compared to the closed ear type devices, such as earphone/headphone, the speaker type personal audio device has advantages of long-time wearing convenience and richer sound spaceness. However, sound leakage around the user may cause noise problems to nearby people, and when used for telecommunication, personal privacy problems may be raised. In order to solve these problems, this study introduces a method of generating a personalized sound field by maintaining sound pressure around the user's head and attenuating sound leakage in fields far from the head. First, using 2 to 4 speakers each on the left and right located near the user's head, the acoustic path response to the ear and the multiple position of azimuth 15 degrees and elevation 10 degrees apart at a distance of about 1m from the head were measured. And then, a multi-channel filter satisfying the above target conditions was designed by the Multiple-Input/Output Inverse Theorem (MINT) method. As a result of simulation and measurement, it was confirmed that the acoustic contrast can be obtained a maximum performance of about 30dB.