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Noise Control in Home Environment
Supervisor: Håkan
Hjalmarsson
Examinator: Håkan
Hjalmarsson
Project background
Disturbing noise is nowadays a major
problem in the society as a whole. In the home environment I have always
thought that the vacuum cleaner is a noise making monster. But I had never
though about a solution until I took a course in adaptive signal processing.
In that course I realized that the solution maybe isn't so far away. That's
why I want to do this thesis project.
Prior work in this area has been focused on improving low frequencies
attenuation in passive ear protectors with active noise attenuation
techniques. The new in this thesis project is that only active noise
attenuation techniques will be used. The implementation to vacuum cleaner
noise attenuation is also new.
Solution
The problem is to generate a signal that destructively interfere
with the disturbing noise in the vicinity of the ear but don’t affect useful
signals. In this project a control DSP is used that adaptively
manipulates a measured noise reference and feeds the resulting
signal to a pair of open headphones. The superposition of the noise
sound and the sound field from the earphones destructively
interfere. Useful signals isn’t affected. A error microphone
close to the ear monitors the performance of the attenuation. One DSP is used for each ear
cup of the headphones.
The algorithm used is the Fx-LMS algorithm. This algorithm
automaticly compensates for changes with time and nonstationarities.
Documents
References
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