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.

最近已经提出了用于音频应用程序的参数阵列的实际开发。实际上，大多数演讲者都是方向性的。但是，参数扬声器是明显的。具有狭窄音频梁（如聚光灯）的高定向性声音系统可以将声音传输到相邻位置无法检测到的特定区域。在本研究项目中开发了一些新技术，例如适当的信号处理以改善谐波失真，并将其应用于可听见的交通信号，该信号为直线通行提供了可靠的指导。从演讲者发射器的发射器对载体超声检查的实际调节是使用音频信号（例如语音）的信封来减少扬声器工作中的电力消耗。首先，我们已经制造了一个具有数字信号处理器的信封调制器，并明确指出，与常规振幅调制相比，工作人员的功率减少了36％。其次，我们专注于提高电力到声力的转化效率。通过与超声发射器的输入端子并联连接适当的线圈，我们能够减少发射极中的反应电流，从而合理地提高功率效率。对于语音和音乐节目，通过连接线圈，平均电力实际上降低了约30％。此外，讨论了带有包膜载体的SSB的前瞻性调制方法，以减少参数声音的失真。与传统扬声器相比，使用具有尖锐定向性的参数扬声器发出的可听见的交通信号更本地化。最后，使用参数扬声器的使用实验表明，视力障碍的行人可以完成穿越人行横道，从而提供了可靠的指导，可以直接穿过街道。