Development of a high-directivity speaker system for improving sound environment

开发改善声音环境的高指向性扬声器系统

基本信息

批准号：
15310117
负责人：
KAMAKURA Tomoo
金额：
$ 6.34万
依托单位：
The University of Electro-Communications
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Practical development of a parametric array for audio applications has been advanced recently. Actually, most speakers are directional. However, the parametric speaker is directional remarkably. High directivity sound systems having narrow audio beams like a spotlight can transmit a sound to a specific area that cannot be detected by people in adjacent locations. Some new technologies such as appropriate signal processing to improve harmonic distortion are developed in the present research project with an application to an audible traffic signal which provides reliable guidance for going straight across the street. A practical modulation of the carrier ultrasound from an emitter of the speaker is to use the envelope of audio signals such as speech to reduce electric power consumption in working the speaker. First, we have fabricated an envelope modulator with a digital signal processor and made clear that the speaker in working consumes less power with 36% reduction compared with a conventional amplitude modulation. Second, we have focused on improvement of the conversion efficiency from electric power to acoustic power. By connecting an appropriate coil in parallel with the input terminals of the ultrasonic emitter, we were able to reduce reactive current in the emitter, improving the power efficiency reasonably. For speech and music programs, the average electric power was actually reduced by about 30% by connecting the coil. Moreover, the prospective modulation method of SSB with an envelope carrier is discussed to reduce distortion in parametric sounds. Using audible traffic signals emitted from a parametric speaker with sharp directivity are more localizable in a crosswalk than those from a conventional speaker. Last, the use of the parametric speaker has experimentally demonstrated that visually impaired pedestrians can complete the crossing with less getting out of the crosswalk, providing reliable guidance for going straight across the street.

用于音频应用的参数阵列的实际开发最近取得了进展。事实上，大多数扬声器都是定向的。然而，参量扬声器的方向性非常好。具有窄音频束（如聚光灯）的高指向性音响系统可以将声音传输到相邻位置的人们无法察觉的特定区域。目前的研究项目开发了一些新技术，例如改善谐波失真的适当信号处理，并将其应用于可听交通信号，为直行过马路提供可靠的指导。对来自扬声器的发射器的载波超声的实际调制是使用诸如语音的音频信号的包络来降低扬声器工作时的电力消耗。首先，我们制作了带有数字信号处理器的包络调制器，并明确了扬声器工作时的功耗比传统幅度调制降低了36%。其次，我们着力提高电能到声能的转换效率。通过在超声波发射器的输入端并联适当的线圈，我们能够减少发射器中的无功电流，合理地提高功率效率。对于语音和音乐节目，通过连接线圈，平均电力实际上减少了约30%。此外，还讨论了带有包络载波的单边带的前瞻性调制方法，以减少参量声音的失真。使用具有清晰方向性的参数扬声器发出的可听交通信号比传统扬声器在人行横道上更容易定位。最后，参数扬声器的使用通过实验证明，视障行人可以在较少离开人行横道的情况下完成过马路，为直行过马路提供了可靠的引导。