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A Revelation – Intelligible Tunnel PA Systems
The Australian Acoustical Society Conference 2011 was held between the 2nd and 4th of November 2011 on the Gold Coast, Queensland. The conference theme was Breaking New Ground.
Papers were presented on areas of acoustics associated with major infrastructure, transportation, industry and mining. Other major topics for the conference included; underwater acoustics/marine bioacoustics, architectural and building acoustics, music acoustics, wind turbines and low-frequency noise.
Peter Ridley and David Spearritt presented a paper on behalf of Stacey Agnew Pty Ltd, Evaluation of Speech Transmission in a Road Tunnel.
Long reverberation times and high background noise levels associated with jet fans degrade speech transmission in road tunnels. Experimental measurements of sound attenuation and reverberation time in the Sydney Harbour Tunnel were used to calibrate a mathematical model used to estimate “speech transmission index”. This study forms a basis for future work by Stacey Agnew in the evaluation of acoustic design of public address systems required for communication to motorists who may become stranded within the tunnel during normal operations or tunnel emergencies.
In a tunnel’s design stage it may be possible to make significant reductions to the reverberation time by appropriate selection of surfaces.