Date

6-2012

Degree Name

BS in Electrical Engineering

Department

Electrical Engineering Department

Advisor

Jane Zhang

Abstract

Noise cancellation involves removing an unwanted noise while keeping the source sound. The source sound may consist of speech, music played from a device such as an iPod or a computer, or no sound at all. The objective of this project is to study the process of noise cancellation both as hardware and as software. The hardware will consist of building a noise cancelling circuit that uses headphones as an output, a microphone to pick up the noise to be cancelled and, if desired, a source sound. The software portion of the experiment will use MATLAB to simulate the hardware circuit as well as simulate other methods: filtering unwanted signal, a pi phase shift for inverting the noise signal, the least mean squares algorithm, and the recursive least squares algorithm. The hardware solution works well with periodic noise but has difficulty removing noise from non-periodic noise. The software solution using adaptive filtering works better than the hardware solution but only with periodic noise. Difficulties encountered include the kinds of noise that can be canceled and the time delay internal to the circuit.

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