Design of directional audible sound field in vehicle cabin

• Main Authors: Chen, Chun-Yi, 陳俊屹
• Other Authors: Tseng, Wen-Kung
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/92919920938965363067

碩士 === 國立彰化師範大學 === 車輛科技研究所 === 99 === Vehicle safety has been improved by the manufacture in recent years. Comfortable riding has also been considered as an important factor. If passengers in vehicle cabin can listen to their favorite music or information without disturbance each other, then the comfortable driving will be improved significantly. In general the audible sound has the characteristics of spreading, however the ultrasound is directional. This study used amplitude-modulating technique for an array of 8 ultrasonic transducers to produce directional audible sound beam. Therefore different passengers in vehicle cabin can listen to different music. In this study sound field distribution for the directional audible sound beam has been investigated. The effect of different weightings varied with different frequency for the transducers on the directivity of the sound beam has also been evaluated. control was used to calculate the optimal weightings of the transducers for better directivity of the sound beam. Different optimal weightings also added to the carrier and sideband frequencies to control the difference frequency’s beamwidth and sidelobe amplitude. Most importantly, the proposed system can steer the difference frequency to a good directivity of the sound beam. Experimental results have been compared with the simulation results. The results showed that the beam width can be controlled and good directivity of the sound beam can be obtained by using control.