Kaiapoi Borough School Hall

Pre-Test

An RT60 reading was done prior to installing acoustic panels on the ceiling. The results below show a reverberation time of approximately 2 seconds between the initial clap and the sound falling below 60 Db (effective silence). The hall was not extremely reverberant but definitely needed acoustic treatment if it is was to be used for a variety of teaching, sporting and performance activities. The aim of this project was to get the reverberation down to less than 1.3 seconds.

Kaiapoi-Borough-School-Hall1-Edited-(1).jpg
 

NB There was a noticeable secondary “slap echo” effect shown on the diagram below by the minor peak between 1.4 and 1.9 seconds and this was annoying when trying to converse in the hall. 

Kaiapoi Borough School Hall Pre Test.png
 

Post-Test

A second RT60 test was carried out once all 168 (1150mm x 580mm x 50mm) white Polyester ceiling acoustic panels were installed – results shown below.

NB There were no other structural changes, wall or floor cladding changes to the interior of the hall between the two readings 

Kaiapoi Borough School Hall Post Test.png
 

Results and Conclusions

  1. The RT60 reading is now around 1 second. This is an excellent result for any hall/gymnasium.

  2. During this second measurement I was able to converse with a builder 7 metres away at the top of a scissor lift in a normal speaking voice and understand every word.

  3. This is one of the best sounding halls I have heard in New Zealand.

  4. The reasons for these results are:

    1. The installers glued the panels exactly as we specified i.e. evenly over the entire surface of the ceiling with a minimum gap of 200mm between panels.

    2. The panel edges are exposed which increases their sound absorption by 25%.

    3. The panels are 50mm thick which means we are addressing not just higher (voice frequencies) but also the more troublesome mid and lower mid frequencies (e.g. running feet and bouncing basket balls).

    4. The acoustic panels are not hidden behind a slotted, perforated or grid surface where they are only 10-15% effective. These panels are fully exposed and therefore 100% effective.

    5. The above four factors are why such dramatic results can be achieved with so few panels and at a very moderate price.

 
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