Acoustic noise cancellation

Active cancellation of acoustic noise by subtracting a pressure wave equal to the original wave is a relatively new development made possible by the progress of VLSI for signal processing. This paper concerns an active noise cancellation system which was built around a Texas Instruments TMS 32010 signal processing microprocessor. The final system will consist of a source microphone providing a sample of the unwanted signal, a reference microphone located at the site where the noise is required to be cancelled and a loudspeaker located between the noise source and the reference microphone. The signal from the source microphone is processed by an adaptive filter and transmitted by the loudspeaker with the exact phase and amplitude required to cancel the original sound wave.