Background
We received a call from the Aycliffe Community Centre asking us how to reduce echo in a hall. The space is a multi-purpose hall space, mainly leased to Youth Club events such as; Cubs, Scouts and other similar events which require a large floor space due to the number of participants involved.
It can be so hard to communicate effectively in a hall with a reverberation issue. It can also cause large groups to get incredibly loud as everyone speaks louder and louder to be heard over the echo!
Don’t worry though. there is actually a very easy and well-proven fix to this problem, acoustic panels! These panels are designed to absorb sound and stop it from bouncing around the room causing echo problems. The
- Measured at 15m x 7m x 6.3m (height)
- Abundance of reflective surfaces which contributes to extended reverberation times
- 3.5-4 seconds estimated Reverberation Time
With this space, it was an issue with internal reverberation which creates a difficult environment to educate and give clear instructions to because of the Reverberation Time being beyond 3 seconds where in a large hall are ideally between 0.8 and 1.5 seconds.
“Assembly hall, multi-purpose hall (drama, PE, audio/visual presentation, assembly, occasional music), New Build 0.8- 1.2 Existing Build 0.8 – 1.5 1” from BB93 document.”
How to reduce echo in a hall (the research)
When reviewing the research into the effects of Reverberation on education and understanding speech, it is still early in its development – some cases believing it can hinder learning in the long term as well as reducing perceived attention in class rooms that could be very important in active exercises and engaging in the activity.
“Regarding the speech intelligibility test applied to students, it was observed that children performed better in classrooms with lower values of Leq, shorter reverberation time, and increased STI, and these associations were statistically significant. These data show that the acoustic parameters directly influence the intelligibility of speech in the classroom and can interfere with the understanding of what is said by the teacher and may even impair learning. Studies agree with the statement that noise can interfere with activities in the classroom(3,10,13). Chinese study states that the intelligibility of speech depends on the acoustic parameters such as reverberation time, the sound pressure level of the teacher’s speech, and the signal/noise ratio”
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2317-17822014000500360
Key
| Leq = sound level in decibels equivalent to the total sound energy measured over a stated period | STI = Speech Transmission Index, where you are looking to achieve a higher level between 0-1, where 0 is poorly understood, 1 is clearly understood – resulting in clear speech intelligibility |
Solution
iKoustic discussed options with Reverberation treatment in which Soft Note™ 50mm(Wrapped in Beige) was required to blend in with the aesthetics of the space, not wanting to be a standout artistic piece. Soft Note™ 50mm is an A Class Absorber and made of 100% polyester fibre, with no chemical binders or retardants – making it a safer alternative to mineral wool framed materials on the market.
Soft Note™ 50mm was fitted directly above window height to give best coverage for the pitched roof as well as being out of reach of any tampering – we were unable to apply on the ceiling space for the customer did not want to have any coverage in this area. We created a basic visualisation to give the customer a chance to review what we were proposing and the placement of all sound absorption panels.
Results
No formal Reverberation Test was carried out, but in our video shown above – a clear difference can be detected subjectively.
The customer was delighted in the vast improvement of the space.