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Vol 41 No 2

CONTENTS

August 2013


LETTERS

Response to: S. Cooper, ?Wind farm noise - an ethical dilemma for the Australian Acoustical Society??, Acoustics Australia 40(2), 139-142 (2012)
Paul Miskelly
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ARTICLES

An on-demand simultaneous annoyance and indoor noise recording technique
Con J. Doolan and Danielle J. Moreau
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Assessment of an acoustic screen used for sound exposure management in a professional orchestra
Ian O'Brien, Judy Wood and Bronwen Ackermann
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On absorption and scattering coefficient effects in modellisation software
S. Cerd?, R. Lacatis and A. Gim?nez
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An experimental study on the sound absorption of three-dimensional MPP space sound absorbers: Rectangular MPP space sound absorber (RMSA)
Kimihiro Sakagami, Motoki Yairi, Emi Toyoda and Masahiro Toyoda
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The division of the perceptual vowel plane for different accents of English and the characteristic separation required to distinguish vowels
Ahmed Ghonim, Jeremy Lim, John Smith and Joe Wolfe
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Shock waves and the sound of a hand-clap ? A simple model
Neville H. Fletcher
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TECHNICAL NOTES

Noise from other peoples' headsets
Warwick Williams and Tom Harper
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Acoustic redesign of Brisbane City Hall Auditorium
Derek Thompson
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Musical rhythm, vibrato and wind turbine noise
Neville Fletcher
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Concert quality sound for ANZ Stadium
Steve Drury
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News
Standards Australia
New Products
Divisional News
Future Conference
Diary
Sustaining Members
Advertisers Index


An on-demand simultaneous annoyance and indoor noise recording technique

Con J. Doolan and Danielle J. Moreau
School of Mechanical Engineering, The University of Adelaide, Adelaide, Australia

Vol. 41, No. 2 pp 141 - 145 (2013)
ABSTRACT: A novel methodology is presented for the simultaneous measurement of noise and personal annoyance at the exact times
that the affected person is annoyed. The system is described and applied to a test case, a farmhouse close to a wind farm
where the resident claims to be annoyed by noise. The system was successfully able to characterise the level and spectral
content of the noise in the house when the resident was annoyed, and there was some correlation with personally recorded
annoyance level. As the system cannot identify noise sources, no conclusions can be made about noise source; however, the
methodology is shown to be a useful aid for diagnosing the type and severity of an indoor noise problem. To help interpret
the results from this type of testing, a discussion concerning the subjective nature of noise annoyance is presented before
some suggestions are made for further improvements in the measurement system.

Assessment of an acoustic screen used for sound exposure management in a professional orchestra

Ian O?Brien1, Judy Wood2 and Bronwen Ackermann1
1Discipline of Biomedical Sciences, School of Medical Sciences, The University of Sydney, Australia
2The Queensland Symphony Orchestra, Australia

Vol. 41, No. 2 pp 146 - 150 (2013)

ABSTRACT: It has been shown that orchestral musicians risk damage to their hearing from workplace noise exposure. Personal,
administrative and engineered control measures strive to reduce exposure to the musicians while having minimal impact
on the musicians? ability to produce music to the highest standard. Acoustic screens form part of a range of controls used
to manage sound exposure, but their construction and placement needs to be carefully considered in the orchestral setting.
Existing acoustic screens for use in orchestras have been shown to be ineffectual, to exacerbate risk of injury to some
players through qualitative and quantitative changes to the acoustic environment or suffer other practical limitations such
as obscuring sight lines. This study reports on an acoustic screen currently in use designed to protect musicians in front
of high volume instruments while having minimal impact on players of these high volume instruments through the use of
appropriately arranged diffusive and reflective materials. Sound level testing was carried out with the screens in various
positions in the orchestra pit with both pink noise and high level instruments used as a sound source. Additionally sound
levels were monitored during orchestral performances to assess the impact of the screens on actual exposure levels. Results
indicate the screens effectively reduce exposure to those in front of high-level instruments while having a negligible impact
on those producing these high sound levels.

On absorption and scattering coefficient effects in modellisation software

S. Cerd?1, R. Lacatis2 and A. Gim?nez2
1Applied Mathematics Department, Universitat Polit?cnica de Val?ncia, Spain
2Applied Physics Department, Universitat Polit?cnica de Val?ncia, Spain

Vol. 41, No. 2 pp 151 - 155 (2013)
ABSTRACT: This paper presents the results provided by two simulation programs for a very simple model: a cube in which all sides have
the same absorption but different global scattering coefficients. Effects on merit figures of the main acoustic parameters
are shown for scattering changes for a single absorption coefficient. The results are helpful for understanding the role of
absorption and scattering on the values of these parameters.

An experimental study on the sound absorption of three-dimensional MPP space sound absorbers: Rectangular MPP space sound absorber (RMSA)

Kimihiro Sakagami1, Motoki Yairi2, Emi Toyoda3 and Masahiro Toyoda4
1Environmental Acoustics Laboratory, Graduate School of Engineering, Kobe University, Kobe, 657-8501, Japan
2Kajima Technical Research Institute, Tobitakyu, Chofu, 182-0036, Japan
3Kobayasi Institute of Physical Research, Higashimotomachi, Kokubunji, 185-0022, Japan
4Faculty of Environmental and Urban Engineering, Kansai University, Suita, 564-8680, Japan

Vol. 41, No. 2 pp 156 - 159 (2013)
ABSTRACT: A microperforated panel (MPP) is usually placed with a rigid-back wall to form a Helmholtz resonator with its hole and the
air-back cavity. However, the authors have so far proposed an MPP space sound absorber without any backing structure. In
the previous studies, as a basic form of such an MPP space absorber, multiple-leaf MPP structures without a back wall were
proposed, and were theoretically and experimentally examined. In order to provide more unrestricted usage and designs
for an MPP space absorber, the authors have also proposed a three-dimensional MPP space absorber, called a cylindrical
MPP space absorber (CMSA). The CMSA was shown to exhibit resonance peak absorption and additional low frequency
absorption. In this paper, another alternative of a three-dimensional MPP space absorber, a rectangular MPP space absorber
(RMSA) is proposed. Its sound absorption performance is discussed using experimentally measured results. The results
show sound absorption characteristics similar to a CMSA, and an RMSA can be effectively used if properly designed.

The division of the perceptual vowel plane for different accents of English and the characteristic separation required to distinguish vowels

Ahmed Ghonim, Jeremy Lim, John Smith and Joe Wolfe
School of Physics, The University of New South Wales, Sydney NS W 2052

Vol. 41, No. 2 pp 160 - 164 (2013)
ABSTRACT: The results of an on-line study of vowel recognition by English speakers are analysed. A relatively unused region of the
perceptual vowel plane is identified at about (F2, F1) = (1800 Hz, 350 Hz). The rest of the plane is divided among vowels
in ways that differ somewhat for different countries and regions thereof. Vowel length is used in several cases to help
distinguish vowels whose distributions overlap substantially in (F2, F1). When the fundamental frequency is higher, the
values of F1 and F2 are also higher, though much less than proportionally. This is consistent with the observation that
women?s vocal tracts are usually shorter than men?s. The characteristic separations required to distinguish vowels in the
(F2, F1) plane were 115 Hz and 292 Hz in the F1 and F2 directions respectively, with similar values in different countries.

Shock waves and the sound of a hand-clap ? A simple model

Neville H. Fletcher
Research School of Physics and Engineering, Australian National University, Canberra
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 2 pp 165 - 168 (2013)

ABSTRACT: The aerodynamics of the impact between two human hands in a hand-clap is examined, in particular in relation to the hand profile which
may be either nearly complementary between the two hands, giving a nominally flat impact, or else domed so that there is a significant
enclosed volume. It is shown that shock waves are generated in nearly all hand-claps, with the addition of a Helmholtz-type resonance in
the case of domed impacts. As can be judged by simple listening, a flat clap produces broad-band sound that typically extends to about
10 kHz while the spectrum of a domed clap usually has a subsidiary maximum somewhere below 1 kHz and then declines with frequency
more rapidly than does the flat clap.

Noise from other peoples' headsets

Warwick Williams and Tom Harper
National Acoustic Laboratories, Sydney

Vol. 41, No. 2 pp 169 - 170 (2013)
ABSTRACT: Noise leaking from under the headsets of personal stereo users is sometimes found annoying by those in the immediate
vicinity and can be the subject of complaints. Measurements presented here demonstrate that the associated noise levels
should be minimal in nature and not pose a significant source of difficulty for most people.

Acoustic redesign of Brisbane City Hall Auditorium

Derek Thompson
AE COM, Melbourne, VIC, Australia

Vol. 41, No. 2 pp 171 - 173 (2013)
ABSTRACT: Prompted by a need for urgent structural repairs, a $215 million project was initiated by Brisbane City Council in 2009
to restore Australia?s largest town hall. AECOM was commissioned through the architects to provide acoustic advice for
the overall building, including Council Chambers, staff offices, and a new rooftop gallery for the Museum of Brisbane.
AECOM was also engaged to provide specialist architectural acoustic design for restoration of the main Auditorium.

Musical rhythm, vibrato and wind turbine noise

Neville Fletcher
Research School of Physics and Engineering, Australian National University, Canberra
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 41, No. 2 pp 174 - 175 (2013)
ABSTRACT: The nature and origin of frequency and amplitude modulation in music and other related human activities is examined and particular neural ensitivity is identified in the frequency range 1 to 10 Hz. It is surmised that amplitude modulation as the vanes pass the tower may be
a major factor in wind turbine annoyance, and suggested that an electro-acoustic system to reduce this modulation might be effective in
reducing noise annoyance.

 

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