NASA Scientific and Technical Aerospace Reports

National Oceanography Centre, Southampton, and the Schools of Chemistry and Engineering Sciences are also forming the
basis of some exciting new research developments in this area. New appointments in the Human Sciences Group have been
facilitated through the increased income generated by our new undergraduate program in Audiology. This will undoubtedly
in due course help strengthen our research activities in hearing aids and cochlear implants, cochlear and vestibular function,
and related aspects of hearing and research. It will be important in the future for strong collaborations to develop between
researchers in this group and those in other groups in the Institute to ensure that the potentia1 benefits are realized of
cross-fertilization between our expertise in engineering and the human sciences. This also applies to the area of human
response to vibration, in which we have great strength, and upon which we wish to build with significant investment in
equipment and facilities during the forthcoming year. The new building will house a multi-axis simulator facility that will keep
us at the leading edge of activities in this area. . The strengthening of our activities in biomedical signal processing is clearly
producing some exciting developments in this field with a strong participation in the University’s neuroscience initiative being
particularly noteworthy. There is also great potential for work with other Schools at the Life Sciences Interface, especially
through collaboration with the School of Health Professions and Rehabilitation Sciences with whom we are developing an
increasingly close relationship. More traditional areas of activity continue to yield research outputs of high quality, especially
in the fields of active control, auditory and speech modelling and underwater signal processing and control. There also remains
great potential for further exploitation and application of signal processing methods across a wide range of other activities
within the Institute and the University as a whole.
Author
Acoustics; Aerodynamic Noise; Auditory Signals; Fluid Dynamics
20060001587 London Univ., UK
Cancellation of Acoustic Noise in a Pipe Using Digital Adaptive Filters
Flockton, Stuart J.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP ‘87); Volume 1;
1987, pp. 5.8.1 - 5.8.4; In English; See also 20060001583; Copyright; Avail.: Other Sources
This paper describes a series of experiments on the control of acoustic noise by antiphase electroacoustic feedback,
utilizing a 4-chip digital adaptive filter developed by British Telecom Research Laboratories. An active control system must
provide accurate modelling of an acoustic path (for 20dB attenuation the error in magnitude of the modelling must not exceed
10% and the error in phase must not exceed 6 deg), but also a should be made inherently stable despite the closed loop
necessarily formed by the (detector)/(filter system)/(secondary source)/(detector). The system described here overcomes the
problem in two parts. There is a digital adaptive filter arranged to act in the same way as a conventional echo canceller to kill
the feedback loop, and there is a second such filter arranged to provide the required feedforward transfer function for
cancellation to be achieved. The characteristics of these filters are described and also illustrated by experimental results.
Author
Adaptive Filters; Cancellation; Electroacoustics; Feedback
20060001600 Nanjing Institute of Technology, Nanjing, People’s Republic of China
A New Algorithm for Maximum Entropy Image Reconstruction
Wei, Gong; He, Zhen-ya; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP ‘87); Volume
1; 1987, pp. 14.12.1 - 14.12.3; In English; See also 20060001583; Copyright; Avail.: Other Sources
In this paper, we propose a new algorithm for maximum entropy reconstruction of the original image from a part of its
noise corrupted linear measurement. The algorithm we propose here is a iterative way which uses the fast Fourier transform
(FFT) so that it consumes less computer time than others do.
Author
Algorithms; Image Reconstruction; Maximum Entropy Method; Mathematical Models
20060001613 Ecole Nationale Superieure des Telecommunications, Paris, France
Spectral Distribution and Damping Factors Measurements of Musical Strings using FFT Techniques
Chaigne, Antoine J.; IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP ‘87); Volume 1;
1987, pp. 5.5.1-5.5.4; In English; See also 20060001583; Copyright; Avail.: Other Sources
We present a new experimental technique of measuring the partial’s amplitudes and decay times of musical strings, using
a dual channel FFT analyser. Examining the results in terms of the internal losses of the strings shows that the dynamic
stiffness is an important parameter for the temporal evolution of the spectral distribution. We relate these results to perceptual
203