Redução de interferências destrutivas em arranjos de altofalantes utilizando processamento digital de sinais

Abstract

The use of devices for digital audio processing in real time is becoming more and more common. From the earliest studies in the area of audio and acoustics it is shown the possibility of controlling the wavefront reproduced by several sources. With the advancement of technology, the diffusion of the digital signal processors called DSP, and the reduction of the cost of this technology, a device capable of reducing destructive interferences denominated comb filter in a arrangement of loudspeakers has been proposed. The device is user-friendly and configurable through its own interface. An approximation function was developed to calculate parameters to be inserted in a DSP in order to alter the characteristics of the original audio, such as phase and time, controlling the destructive interferences at a given point in the space. The function was programmed, and through the use of specific platforms for programming microcontrollers and DSPs, was implemented in a prototype capable of performing such control. Acoustic measurements were made of the sound system containing the developed device, the measurements are in an acoustically controlled environment, in order to prove the efficiency of the device. The measurements cover data such as frequency response, impulse response and total harmonic distortion (THD) of the mounted test system. The results obtained present a more homogeneous frequency response at the point of analysis, controlling a common problem in the composition of sound waves radiated by two or more sound sources, comb filter. It was possible to show an improvement of the THD of the system with the control device. It is concluded that the proposed device is able to reduce destructive interference in a loudspeaker array, improving the quality of the audio at the chosen point in the space, providing a new experience for the users of the device.