Design and Implementation of Sound Projector Using a 30-Element Loudspeaker

Abstract

For many years, the surround sound effect could only be fully experienced by setting up several speakers, which required considerable wiring for installation in a typical room. Digital sound projectors, one of the most sought-after state-of-the-art solutions, use an array of small speakers enclosed in a box to provide surround by creating virtual sound sources around the listener. This thesis presents a DSP implementation of a simple digital sound projector based on a uniform linear array of thirty loudspeakers. Surround is produced by controlling separate beams of sound. These are reflected off the walls and arrive at the listener’s position from the desired directions. Due to hardware constrains, the bandwidth of the sound is limited. In order to estimate the direction of the sound at the listener, two techniques based on estimating the time difference of arrival (TDOA), Classical Cross-Correlation (CC) and Cross-Correlation with the Source Signal (CSS), are compared. Objective test results show that the CSS technique is more robust than CC under noisy environments, while both techniques behave similarly in quiet conditions. Subjective and objective results show that this implementation of a sound projector is successful, even if front virtual channels are better perceived by the listener than the rear channels.