Cobb, Benjamin Jon (2006) Directional microphone array for security applications. [USQ Project]
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Abstract
This project investigates the potential for microphone arrays within a security setting,
particularly through exploiting their ability to change their directivity pattern, thus,
changing its direction of hearing.
In single microphone systems speech and other signals of interest can be severely degraded
when recorded in real environments. Security and surveillance systems are no
exception to this rule and therefore microphone arrays have the potential to supplement
the range of listening devices already available.
This dissertation presents the work covered, which includes:
• The potential need for microphone arrays in security settings.
• The legal implications of using microphone arrays in surveillance.
• The concepts of beamforming and the theory behind three common beamformers,
including the Delay and Sum beamformer, the Adaptive Frost beamformer and
the Generalized Sidelobe Canceller beamformer.
• Tests conducted on the beamformers to determine their performance with different
parameters and different types of data.
It was concluded that both the Frost beamformer and the Generalized Canceller both
have the potential to be used in a security setting. The best performance was achieved
with the Frost beamformer with an array size of eight microphones and a tapped-delay
length of 131.
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