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Vol 24 No 2

CONTENTS

August 1996


ARTICLES

Timbre and Loudness of Flute Notes
H Pollard
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Progress in Underwater Acoustic Geo-mapping Technology
S Zhang
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Real Time, Non-lnvasive Measurements of Vocal Tract Resonances: Application to Speech Training
A Dowd, J Smith & J Wolfe
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Condition Monitoring of Bearings in a Viaduct
C H Chew
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Comments On Environmental Noise Assessment
B Murray
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Timbre and Loudness of Flute Notes

Howard Pollard
6 Wren Place
Cronulla, NSW 2230

Vol. 24, No. 2 pp 45-46 (1996)
ABSTRACT:Spectrum analysis of flute sounds published by Fletcher [J. Acoust. Soc .Am. 57, 233-237 (1975)] has been used to compute loudness level and tristimulus coordinates for three notesC4, Cs, C6 played both loud and soft by four players. The differing timbre values for the same note played by the four flutists and the differences between loud and soft notes are clearly revealed in tristimulus diagrams.

Progress in Underwater Acoustic Geo-mapping Technology

Shuying ZHANG
Shanghai Acoustics Laboratory, Academia Sinica
456 Xiao-Mu-Qiao Rd.
Shanghai 200032 China

Vol. 24, No. 2 pp 47-51 (1996)
ABSTRACT: The Shanghai Acoustics Laboratory of Academia Sinica has been involved in the development of underwater sound-sources and geo-acoustic processing techniques over the past 30 years. A range of underwater acoustic mapping systems (geo-sonar systems, and suspended-sediment monitoring systems) has been produced for applications in harbour construction, waterway dredging, seafloor engineering, marine resource exploitation and marine geological studies. The features and performances of these systems are described, and several new techniques employed in their implementation, pulse-compression with complementary coding signals and pattern recognition of acoustic profiling records, briefly introduced.

Real Time, Non-lnvasive Measurements of Vocal Tract Resonances: Application to Speech Training

Annette Dowd, John Smith and Joe Wolfe
School of Physics
University of New South Wales
Sydney 2052

Vol. 24, No. 2 pp 53-60 (1996)
ABSTRACT: This study reports the determination in real time of the frequencies of the first two resonances of the human vocal tract from measurements of the acoustic impedance spectrum of the tract in parallel with the external field. The measurements were made using a broad band, frequency-independent acoustic current source, a microphone and a spectrum analyser which displays the acoustic impedance spectrum. The display provided real-time, visual feedback whereby subjects learned to imitate target vowel sounds without hearing them. Inexperienced subjects who used this feedback produced sounds that were approximately as well recognised as those produced by the same subjects imitating target vowel sounds after listening to them. The recognition rate improves with the subjects' experience in using the impedance feedback technique. This non-invasive technique could thus have possible applications in speech training and language teaching.

Condition Monitoring of Bearings in a Viaduct

C. H. Chew
Department of Mechanical & Production Engineering
Natinal University of Singapore
Kent Ridge Cresent, Singapore 0511

Vol. 24, No. 2 pp 61-66 (1996)
ABSTRACT: The bearings used under the viaducts of the mass rapid transit system are of the scaled type. Though this type of bearings is useful in preventing the elastomer from exposure to ultraviolet light and the elements, it has the drawback of preventing the visual inspection of the physical condition of the elastomer. By measuring the end displacements of the viaduct, we could correlate the peak-to-peak displacements with the elasticity of the elastomer of the bearings used. Analysis shows that the ballast stiffness has very little influence over the end displacements, and the variations of the end displacements are more affected by the stiffnesses of the bearings than the variation in passenger load.

Comments On Environmental Noise Assessment

Barry Murray,
Director, Wilkinson Murray Pty Limited
(Member of the Association of Australian Acoustical Consultants)

Vol. 24, No. 2 pp 67-69 (1996)
ABSTRACT: The ambient background noise level at most locations varies throughout the day and from day to day. In addition, noise levels emanating from an operating plant are also likely to vary from hour to hour and day to day. A method of allowing for these variations in setting environmental noise criteria which are related to community response has been proposed with the purpose of opening discussion on this issue.

 

Newsflash

PROPOSED INTERNATIONAL YEAR OF SOUND 2019

Let's make 2019 the International Year of Sound!

Click here to see draft prospectus. Suggestions for major activities that would be truly international to strengthen the application are welcomed.

 

ACOUSTICS 2017

Perth, Western Australia 19-22 November 2017