Archives of Acoustics, 34, 4, pp. 559-577, 2009

A Multi-Channel System for Sound Control in the Open Space

Wojciech CIESIELKA
AGH University of Science and Technology, Department of Mechanics and Vibroacoustics

In the paper, a multi-channel system for sound control is
presented. The system enables creation of the sound space through generation of
the acoustic signals with the help of sixteen independent controlled sound
sources, in accordance with the accepted quality criterion. The heart of the
realized control system is digital filters system and the digital delay lines
implemented in ADSP BF-537, the multi-channel card by Analog Device Company,
equipped with the extension module. Besides the above-mentioned card with the
microprocessor, the system is constructed of a number of subsystems, including
the acoustic signal generation system, the multi-channels power amplifier and
sixteen sound sources equipped with the special closed box enclosures. The
system design was preceded with the laboratory and model-and-simulation
measurements and the verification measurements carried out in the field. The
laboratory tests were made in free sound field conditions in the anechoic
chamber of the Department of Mechanics and Vibroacoustics, AGH University of
Science and Technology. The model-and-simulation research was carried out using
the geometrical methods implemented in the Raynoise package. The final stage of
the work included the tests confirming the operation effectiveness of the
designed and realized system, which were carried out in the open space - in the
selected area. As a part of the model-and-simulate work and the verification
research, the A-sound level and Speech Transmission Index (STI) distributions
were determined in the control area and in the protected area.
Keywords: sound control; multi-channel systems; digital system; creation of the sound space
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