In this paper, we propose a beam-forming speaker based on digitally direct driven speaker system (digital-SP); the proposed speaker employs multibit delta-sigma modulation in addition to a line speaker array and a delay circuit. The proposed speaker can be realized only by D flip-flops and digital-SP. Delay elements are introduced between the mismatch shaper and sub-loudspeakers, and beam-forming is realized without degradation of the noise shaping performance of the multibit DSMBy using a small amount of additional hardware, we can easily control the sound direction. If a beam-forming speaker can be driven digitally, all processes can be performed digitally without the use of analog components such as power amplifiers, and a small, light, high-quality speaker system can be realized. The prototype is constructed using an FPGA, CMOS drivers, and a line speaker array. The effectiveness has been confirmed by using measurement data. A gain of 8 dB or more is measured relative to the normal digital speaker system. And an attenuation of 14.7dB for 40° direction is measured.
Watanabe, Kyosuke; Yasuda, Akira; Ohtani, Hajime; Suzuki, Ryota; Shinkawa, Naoto; Tsuchiya, Tomohiro; Tsuihiji, Kenzo
Affiliation: Hosei University, Koganei, Tokyo, Japan
AES Convention: 127 (October 2009) Paper Number: 7950
Publication Date: October 1, 2009
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