Large-scale loudspeaker array system for sound field reproduction using high-speed 1 bit signal processing

Recently, many techniques of physical sound field reproduction, such asWave Field Synthesis, Higher Order Ambisonics and Boundary Surface Control, have been studied. Since the number of loudspeakers generally increases to control with higher spatial resolution and higher frequency, the system becomes too complicated to be constructed. On the other hand, high-speed 1bit signal processing has been studied widely. The 1 bit audio system has interesting features such as simple circuit implementation, simple signal transmission and no D/A converter. In this study, we proposed the large-scale loudspeaker array system with high-speed 1 bit signal. The system consists of a master and hub systems with sample rate of 4 MHz. The master system reads multi-channel 1bit signal from SSD and transmits it to each hub system. Each hub system drives 32 loudspeakers by CMOS drivers. The master and each hub system are connected with a LAN cable to implement only hub system near the loudspeakers. It is easy to scale the size of system with flexibility thanks to the simplicity of the circuit and signal flow. We conducted preliminary experiments to control its sound directivity. In the future, we are planning to construct 1536-channel sound reproduction system with our proposed system.