Down with noise
Article Abstract:
New digital signal processing technology is being used for active noise control to make passenger cabins quieter and get rid of sounds that disrupt headset communication. Destructive interference can be set up between two sound fields according to Stephen J. Elliott, professor, Inst. of Sound and Vibration Research, University of Southampton, UK. When two sounds fields can be accurately aligned over an acoustic wavelength in space the technique is most effective. Advances in digital signal-processing (DSP) chips have made such efforts practical. Control of tonal noise is far easier than control of random noise and it is not likely that all noise problems can be solved. In the process control community the best known system is internal model control (IMC). Headsets that cut noise are made for military use by Racal Acoustics Ltd. of the UK, Lectret Precision, Singapore, and Bose, Framingham, MA. Other companies whose products are discussed included, NCT Group, Sony, Sennheiser Electronic GmbH, Lord Corp. and Ultra Electronics.
Publication Name: IEEE Spectrum
Subject: Engineering and manufacturing industries
ISSN: 0018-9235
Year: 1999
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Exploring the third dimension
Article Abstract:
The features of the 3Dconnexion's SpaceNavigator, which is useful in computer aided design of the product, are presented.
Publication Name: IEEE Spectrum
Subject: Engineering and manufacturing industries
ISSN: 0018-9235
Year: 2007
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