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Simplified room acoustic measurement

torhalm.jpg Tor Halmrast

Mr Tor Halmrast from Norway had a very interesting lecture about how to measure reverberation time, and how important it is to be a good “cougher”.

Tor works with music and acoustics. When he is on holiday, he often finds interesting rooms what he wants to measure. To measure room acoustic parameters today requires a lot of equipment that you seldom bring with you. That is why Mr Halmrast bought a small Wav-recorder and some balloons.

So when he finds an interesting building, he blows up a balloon, bursts it and records the sound with the Wav-recorder. When he comes home he calculates the RT by analysing the recordings. He has compared this measurement with the modern equipment like WinMLS and found that the old balloon-measurement gives approximately the same result for reverberation time from 250 – 4000 Hz. But you can not use it to calculate Clarity.
A person in the audience said: It is important to burst the balloon from above because if you burst it from the side you will have to much direct sound and that is not good then you measure the reverberation time.
Mr Halmrast said that it was interesting information and added: – Sometimes I cough and use that as the sound source to measure the reverberation time. He ended his presentation with saying: – I am a very good “cougher”.
By Jonas Christensson, Concept Developer – Modern Office, Ecophon Sweden.
Read more about Tore Halmrast

Acoustic Standards 77

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