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Vol 34 No 3


December 2006


Non-noise contributors to hearing loss
Marion Burgess and Warwick Williams
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Adaptive optimisation for telephony
Christi Wise, Bonar Dickson and Peter Blarney
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Custom-moulded earplugs
Warwick Williams
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Changes in environmental noise measurement
Philip J Dickinson
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Critique of ISO 354 (Acoustics ? Measurement of sound absorption in a reverberation room)
Byron Martin
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Marion Burgess
Acoustics and Vibration Unit,
UNSW@ADFA, Canberra, ACT 2600
Warwick Williams
National Acoustics Laboratory,
126 Greville St, Chatswood, NSW 2067

Vol. 34, No. 3 pp 109 - 114 (2006)
ABSTRACT: Noise exposure at work is a major workplace occupational health problem. Legislation exists internationally and throughout Australia requiring limits to the occupational noise exposure of employees. There are clear standards specifying the noise exposures above which noise management plans to protect the hearing of the employees must be implemented. It has been acknowledged for some decades that, in addition to hearing loss, high levels of noise can cause other adverse health effects. There is now increasing evidence that the combination of non-noise factors in the work environment plus noise can lead to a greater hearing loss than would be experienced from the noise alone. This paper provides a review of the effects of the various factors and comments on their importance for consideration when undertaking occupational noise exposure assessments in the workplace.


Christi Wise*, Bonar Dickson, and Peter Blarney
Dynamic Hearing Pty Ltd, Chapel Street, Richmond VIC 3121, Australia
*Electronic Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Vol. 34, No. 3 pp 117 - 121 (2006)
ABSTRACT: ADRO? is a sound processing strategy implemented in a headset amplifier with acoustic shock protection for call centres. An initial experiment established the feasibility of maintaining high intelligibility of speech in ambient noise levels up to 75 dBA without amplifying speech to uncomfortable levels. In another experiment, ten normally hearing listeners compared the ADRO device with a device used in many Australian call centres. In background noise, the ADRO device provided higher speech intelligibility scores on the Phonetically Balanced Monosyllable word test than the comparison device, and was preferred in 95% of cases. These results suggest the possibility of improving communication and working conditions in call centres and other noisy environments.


Warwick Williams
National Acoustic Laboratories
Chatswood, NSW

Vol. 34, No. 3 pp 122 - 124 (2006)
ABSTRACT: Custom-moulded earplugs are often presented as the ultimate in hearing protector technology and attenuation ability. This analysis compared the performance of custom-moulded devices to off-the-shelf earplugs and earmuffs and found that, while custom devices performed better than the ?average? earplug, they were not as good as the ?average? earmuff. The suggestion is made that the standard hearing protector rating specification of SLC8O may not be applicable to custom-moulded devices and perhaps a more individual rating should be used.


Philip J Dickinson
Massey University Wellington, New Zealand

Vol. 34, No. 3 pp 125 - 129 (2006)
ABSTRACT: Many changes have occurred in the last seventy years, not least of which are the changes in our environment and interdependently our intellectual and technological development. Sound measurement had its origins in the 1920s at a time when people were still traveling by horse and cart or on steam trains and few people used electricity. The technology of electronics was in its infancy and our predecessors had limited tools at their disposal. Nevertheless, they provided the basis on which we rely for our present day sound measurements. Since then we have come far, but we still await a solution for the lack of accuracy we have come to accept.