Home Journal
E-mail Print
Acoustics Australia  Logo (3032 bytes)

Vol 41 No 3

CONTENTS

December 2013


LETTERS

Wind farm noise
Peter Alway
PDF Full Paper

ARTICLES

Characterisation of mulloway Argyrosomus japonicus advertisement sounds
Miles J.G. Parsons, Robert D. McCauley and Michael C. Mackie
PDF Full Paper

BEM simulations of diffraction-optimized geometrical noise barriers, with a focus on tunability
Sara Gasparoni, Paul Reiter, Reinhard Wehr, Marco Conter, Manfred Haider
PDF Full Paper

Reproducibility and applicability of ensemble averaged surface normal impedance of materials using an in-situ technique
Nazli Bin Che Din, Toru Osturu, Reiji Tomiku, Noriko Okamoto, Kusno Asniawaty
PDF Full Paper

Acoustic correction using green material in classrooms located in historical buildings
Gino Iannace, Amelia Trematerra, Patrizia Trematerra
PDF Full Paper

Vibration induced due to acoustic excitation in diffuse field conditions
Naveen Garg and Sagar Maji
PDF Full Paper

Inverse Gabor transform for speech enhancement
Mohammed A. Al-Manie and William J. Wang
PDF Full Paper

TECHNICAL NOTES

Reduced conditions on ambient noise levels for in-situ audiometric testing
M. Fisher and W. Williams
PDF Full Paper

Low cost remote data acquisition system
Kristoffer K. McKee, Gareth L. Forbes, Ilyas Mazhar, Rodney Entwistle, Ian Howard
PDF Full Paper

New grandstand at Randwick racecourse
Steve Drury
PDF Full Paper

Richard Waugh - obituary
Jack Rose - obituary
News
Standards Australia
New Products
Divisional News
Future Conference
Diary
Sustaining Members
Advertisers Index


Characterisation of mulloway Argyrosomus japonicus advertisement sounds

Miles J.G. Parsons1, Robert D. McCauley1 and Michael C. Mackie2
1Centre for Marine Science and Technology, Curtin University, Western Australia
2Department of Fisheries, Government of Western Australia
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 196 - 201 (2013)
ABSTRACT: Increasingly, fishes are reported as using acoustic variations in calls for different environmental and social contexts. However, to understand call functions and their associated behaviours it is first necessary to separate and characterise the species call types. During the Austral summer, mulloway (Argyrosomus japonicus), a vocal sciaenid, aggregates to spawn in the lower regions of the Swan River, Western Australia. In situ A. japonicus calls recorded here exhibited call spectral peak frequencies between 175 and 350 Hz and pulse repetition rate of 59 Hz. These swimbladder driven calls were categorised into; short grunts of 1-6 pulses (?Bup?), more predominant as the aggregation forms and separates; long grunts comprising 11-32 pulses (?Baarp?), most prominent in the hours after sunset; and a series of short calls comprising 1-5 pulses (?Thup?) that increase sharply in call rate over a period of tens of seconds. This last category was observed only once or twice each evening. The second category was divided into several types of call where a single audible tone can also be broken into two or more parts, often preceded by one or more short ?Bups? (for example, ?Bup-bup-baarp?).

BEM simulations of diffraction-optimized geometrical noise barriers, with a focus on tunabilit

Sara Gasparoni1, Paul Reiter1,2, Reinhard Wehr1, Marco Conter1 and Manfred Haider1
1AIT, Austrian Institute of Technology, Vienna, Austria
2Technical University of Vienna, Vienna, Austria
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 202 - 206 (2013)

ABSTRACT: Traffic noise is an increasingly important problem with the increase in traffic volume. To counteract this, noise barriers are the most used traffic-noise-abatement tool. In an attempt to reduce the amount of material, and thus the costs for the construction of noise barriers, it is of interest to reduce the height of the barriers. One possibility to reduce the height is to use absorbing materials. This is a good solution but the porosity of these materials makes them very sensitive to clogging by dirt and changes their absorbance and their performance with time. In this paper, non-standard geometrical forms of noise barriers with added devices are investigated. The boundary element method is used to investigate the insertion loss produced by these noise barriers. This method is also used to propose tunable barriers that could adapt to the changing noise spectrum.

Reproducibility and applicability of ensemble averaged surface normal impedance of materials using an in-situ technique

Nazli Bin Che Din1?, Toru Otsuru2, Reiji Tomiku2, Noriko Okamoto3 and Kusno Asniawaty4
1Faculty of Built Environment, University of Malaya, 50603 Kuala Lumpur, Malaysia
2Department of Architecture and Mechatronics, Oita University, 700 Dannoharu, Oita 870-1192, Japan
3Department of Architecture, Ariake National College of Technology, 150 Higashihagio-Machi, Omuta Fukuoka 836-8585, Japan
4Department of Architecture, Hasanuddin University, Makassar, Jl. Perintis Kemerdekaan Km.10, 90245 South Sulawesi, Indonesia
* This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 207 - 212 (2013)
ABSTRACT: This paper investigates by experiment the absorption characteristics of several materials associated with the proposed acoustics impedance method using the combination of sound pressure and particle velocity sensors in various sound fields. This method is based on the concept of "ensemble averaged" surface normal impedance that extends the usage of obtained values to various applications such as architectural acoustics and computational simulations. The measurement technique itself is an improvement of the method using two-microphone technique and diffused ambient noise. A series of measurement in different sound fields was conducted to expand the relevant applicability of in-situ measurement using pu-sensor. The first part of the experiment aimed to confirm the reproducibility of the measured values of the method. Here, comparative round robin measurements in four reverberation rooms were conducted. The general tendencies and discrepancies of ten materials in the various reverberation rooms are discussed. In the second stage, the method was applied with four types of selected materials to examine material?s absorption characteristics at different sound fields such as in architectural spaces. This paper revealed the reliability, applicability and robustness of the method despite the room?s geometrical differences throughout the in-situ measurement.

Acoustic correction using green material in classrooms located in historical buildings

Gino Iannace, Amelia Trematerra, Patrizia Trematerra
Department of Architecture and Industrial Design, Second University of Naples, Borgo San Lorenzo Aversa, Italy
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 213 - 218 (2013)
ABSTRACT: The acoustic correction inside classrooms located in historical buildings using absorbent panels is difficult for aesthetic reasons. Furthermore, architectural restrictions are often imposed to preserve the historical heritage. The acoustic measurements inside the classrooms show high reverberation time values, which imply an adverse environment for speech reception. In this paper the reverberation time in classrooms located in historical buildings was reduced by installing removable sound absorbent panels. The panels were made with ?green material?. The absorbent material was obtained by crushing giant reeds of sweet water, a plant which grows quickly in wetlands. The crushed material was then put in jute sachets, installed in the wooden frames and covered with different colours jute cloth for aesthetics. Acoustic measurements were made in the classrooms with smooth plaster walls, without students. A virtual model of the classroom was drawn with 3D CAD. The surface area covered with green material absorbent panels was evaluated by the software Odeon. After the installation of the absorbent panels, comparisons between the virtual classroom acoustic properties and the real classroom acoustic properties were made to validate the effect of the green absorption panels.

Vibration induced due to acoustic excitation in diffuse field conditions

Naveen Garg1,2 and Sagar Maji2
1Apex Level Standards & Industrial Metrology Division, CSIR - National Physical Laboratory, New Delhi, India
2 Department of Mechanical, Production & Industrial Engineering, Delhi Technological University, Delhi, India
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 219 - 224 (2013)
ABSTRACT: The paper presents an experimental approach to quantify the vibrations induced due to acoustic excitation in diffuse field conditions. An empirical formulation correlating the varying sound field and vibration level generated in floors and walls in diffuse field conditions has been developed. A lower limiting frequency of 125 Hz for good diffusion is observed due to random wide band acoustic excitation in diffuse field conditions, below which lower vibration levels are registered due to discrete room modes.

Inverse Gabor transform for speech enhancement

Mohammed A. Al-Manie1 and William J. Wang2
1Computer Research Institute, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia
2School of Engineering and Information Technology, University of Sussex, Brighton, BN1 9QT, England
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 225 - 231 (2013)

ABSTRACT: In this paper, the Inverse Discrete Gabor Transform (IDGT) is proposed for signal recovery buried in board-band nonstationary noise. Time-frequency masking filtering technique is implemented to reject the noise from corrupted speech while at the same time maintaining the desired waveform. A synthetic multicomponent non-stationary test signal made up of two chirps was first used to simulate noise; the signals were then separated using this technique. Four English speech signals recorded in different environments such as airport, restaurant, and train buried in wide-band noise were reconstructed. The extracted signals were then compared with the original ones in terms of cleanness and noise removal. The implemented procedure is suitable for this type of wide-band non-stationary interference, which cannot be canceled in the Fourier (frequency) or time domain.

Low cost remote data acquisition system

Kristoffer K. McKee, Gareth L. Forbes, Ilyas Mazhar, Rodney Entwistle and Ian Howard
Department of Mechanical Engineering, Curtin University, Perth, Australia, and CRC for Infrastructure and Engineering Asset Management, This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 3 pp 234 - 237 (2013)
ABSTRACT: Remote data acquisition (RDAQ) is required in a number of vibration and noise measurement settings. Specialised systems exist for RDAQ, however they require significant investment to set up. This paper describes a low cost method of RDAQ which utilises a laptop computer, data acquisition system and a USB internet dongle. The system described in this paper would allow a professional vibration/noise measurement specialist to modify their existing data acquisition system for remote use with minimal cost. The system was tested both in an industrial and an academic setting for verification.

 

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