| Vol 39 No 2 | CONTENTS | August 2011 |
ARTICLES
Acoustic characteristics for effective ambulance sirens
Carl Howard, Aaron Maddern and Elefterios Privopoulos
Full Paper
The fundamentals of power ultrasound – a review
Thomas Leong, Muthupandian Ashokkumar and Sandra Kentish Full Paper
Target speech extraction in cocktail party by combining beamforming
and blind source separation
Lin Wang, Heping Ding and Fuliang Yin Full Paper
TECHNICAL NOTES
Cost effective design for a music rehearsal studio
Derek Thompson Full Paper
Noise exposure reduction for orchestral musicians
W. Williams and G. Stewart Full Paper
Low noise fans for UK cooling towers
Martin Huis in ‘t Veld Full Paper
Book Review
News
New Products
Meeting Reports
Standards Australia
Future Conference
Colin Speakman Obituary
Diary
Sustaining Members
Advertisers Index
Acoustic characteristics for effective ambulance sirens
Carl Q. Howard, Aaron J. Maddern and Elefterios P. Privopoulos
School of Mechanical Engineering, The University of Adelaide, Adelaide, South Australia
Vol. 39, No. 2 pp 43 - 53 (2011)
ABSTRACT: Ambulances involved in collisions with motorists at intersections result in a number of negative outcomes including the inability to respond to the assigned emergency task, injury of people, and sometimes the loss of an operational appliance. The warning siren is perhaps the only non-visible device to alerting motorists approaching intersections of a converging ambulance. Acoustic measurements were conducted on several commercial-off-the-shelf sirens, a motor vehicle, and an ambulance, to characterise the noise transmission system. Tests were conducted in order to provide recommendations to improve the audibility and effectiveness of the warning signal. It is recommended that ambulance operators install sirens that broadcast sideways to the ambulance; that broadcast low frequencies so that the siren sound can penetrate into vehicle cabins; and that have signals with short repetition periods to convey high perceived-urgency.
The fundamentals of power ultrasound – a review
Thomas Leong, Muthupandian Ashokkumar and Sandra Kentish*Department of Chemical & Biomolecular Engineering and School of Chemistry,
University of Melbourne, VIC 3010
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Vol. 39, No. 2 pp 54 - 63 (2011)
ABSTRACT: The principal method behind applications of power ultrasound is that of acoustic cavitation. This paper aims to provide an overview of bubble behaviour during acoustic cavitation, including phenomena such as transient and stable cavitation, rectified diffusion, coalescence and sonoluminescence. Application of these effects to processes such as nanomaterial synthesis, emulsion formation and waste water treatment is then described.
Target speech extraction in cocktail party by combining beamforming and blind source separation
LinWang1,2, Heping Ding2 and Fuliang Yin11 School of Electronic and Information Engineering, Dalian University of Technology, P. R. China
2 Institute for Microstructural Sciences, National Research Council Canada
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Vol. 39, No. 2 pp 64 - 68 (2011)
ABSTRACT: Due to the ambient noise, interferences, reverberation, and the speakers moving and talking concurrently, it is a challenge to extract a target speech in a real cocktail-party environment. Emulating human auditory systems, this paper proposes a two-stage target speech extraction method which combines fixed beamforming and blind source separation. With the target speaker remaining in the vicinity of
a fixed location, several beams from a microphone array point at an area containing the target, then the beamformed output is fed to a blind source separation scheme to get the target signal. The fixed beamforming preprocessing enhances the robustness to time-varying environments and makes the target signal dominant in the beamformed output and hence easier to extract. In addition, the proposed method does not need to know the knowledge of source positions. Simulations have verified the the effectiveness of the proposed method.
Cost effective design for a music rehearsal studio
Redevelopment of Victoria Police Bands’ Green Street StudiosDerek Thompson, AECOM
Vol. 39, No. 2 pp 69 - 72 (2011)
ABSTRACT: The Victoria Police Bands perform at formal police events, official State functions, in schools, for charities, and at community events throughout Victoria. From their permanent base – in an almost forgotten corner of Melbourne’s inner northern suburbs – the bands often host school groups, provide music education workshops, conduct master classes, and even record and produce their own CD releases for sale. This month the band moves into a dedicated new rehearsal facility, recently completed on their existing site. This brief note summarises the vision and constraints driving the project, and traces the broader design process behind the acoustic design.
Noise exposure reduction for orchestral musicians
W. Williams and G. Stewart
National Acoustic Laboratories, Chatswood, NSW
Vol. 39, No. 2 pp 73 - 74 (2011)
Low noise fans for UK cooling towers
Martin Huis in ‘t VeldSales Manager Retrofit, Howden Netherlands b.v.
Vol. 39, No. 2 pp 75 - 76 (2011)
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