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Vol 21 No 2

CONTENTS

August 1993


ARTICLES

Impact Descriptors Versus Exposure Indices In Environmental Assessment
A J Hede

Improving The Acoustic Performance of Preformed Thermal Pipe Insulations
K P Byrne

Water, Movement and Sound A Musical Sculpture At Hornsby, NSW
N Clark, V Cusack, S. Thwaites

The Development of Acoustic Volume Velocity Sources
K P Byrne

INTERVIEW

Howard Pollard
Graham Caldersmith

 

News and Notes
Books Reviews
New Products
Advertisers Index
AA & Society information
Diary


Impact Descriptors Versus Exposure Indices In Environmental Assessment

Andrew J. Hede
Department of Government, Economics & Logistics
University of Southern Queensland
Toowoomba, Qld, 4350

Vol. 21 No. 2 pp 41 - 44 (1993)
ABSTRACT: Environmental noise impact in Australia is measured indirectly using noise exposure indices rather than directly in terms of impact descriptors. This focusing on exposure rather than on impact can result in environmental assessments which seriously under-estimate the true noise impact of a development proposal on residential communities. This article recommends the use of impact descriptors in addition to an exposure index to ensure that assessments provide developers, residents and decision-makers with a complete picture of potential impacts. Aircraft noise is used as an example to illustrate how impact descriptors can be applied.

Improving The Acoustic Performance of Preformed Thermal Pipe Insulations

K.P. Byrne
School of Mechanical and Manufacturing Engineering
The University of New South Wales
Kensington NSW 2033

Vol. 21 No. 2 pp 45 - 50 (1993)
ABSTRACT: Preformed thermal pipe insulations intended to control heat transfer to and from small diameter pipes are manufactured in Australia from plastic foams and fibrous materials in a wide range of sizes. It has been found that when preformed thermal pipe insulations are applied directly to pipes which are radiating sound, the insulated pipes generally become more effective radiators at low frequencies. This is presumably due, in part at least, to the fact that a preformed thermal pipe insulation, being moulded or extruded to fit closely onto a specific pipe, can be forced to vibrate by the vibrating pipe wall and being of larger diameter than the bare pipe, radiates more sound than the bare pipe. This paper presents the results of sound intensity measurements which were made to assess the improvement in the insertion loss which is associated with fitting these preformed thermal pipe insulations so that there is an air gap between the pipe and the insulation. Measurements to assess the effect of wrapping preformed thermal pipe insulations with a limp impervious barrier are also presented. The data presented in the paper are intended to aid in the effective acoustic use of the preformed thermal pipe insulations which are widely used in Australia.

Water, Movement And Sound A Musical Sculpture At Hornsby, N.S.W.

N.Clark*, V.Cusackt, S.Thwaites*
* C.S.I R.O Division of Applied Physics
PO BOX 218, Lindfield, NSW, 2070
tFineArt Bronze Foundry
99 McCarrs Ck Rd
Church Point, NSW,

Vol. 21 No. 2 pp 51 - 54 (1993)
ABSTRACT: An unusual sculpture in a public square at Hornsby, NSW, includes a 17 note Carillon or Chime Set, of the type known as "Harringtons" Chimes, using Tubular Bells. Some features of such instruments are examined, and some problems in tuning are discussed.

The Development Of Acoustic Volume Velocity Sources

K P Byrne
School of Mechanical and Manufacturing Engineering
The University of New South Wales
Sydney, Australia.

Vol. 21 No. 2 pp 55 - 59 (1993)
ABSTRACT: Acoustic volume velocity sources can be useful in experimental acoustics. They can be used, for example, to determine the particle velocity in formation needed in measuring acoustic impedance. The development of modern signal processing instrumentation has allowed volume velocity sources to be used conveniently. Two volume velocity sources developed at The University of New South Wales are described. One is based on a modified acoustic horn driver and the second is a specially constructed device. The methods used for calibrating the devices are described and the results of a performance test based on measuring the input and transfer impedances of a closed end tube are given.

 

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