Acoustic renovation at Velka Bystrice sports hall, Czech Republic
In the small town Velka Bystrice in Czech Republic, the municipal sports hall plays an integral part of the inhabitants’ lives and daily activities. When built in 2006, the sports hall didn't get any acoustic treatment which led to complaints from trainers, pupils and visitors. An acoustic transformation of the space was needed.
Description of the case
The area of the hall is 1 180 m2 and the volume is 10 224 m3. The floor is made of a modern rubber surface, the walls are plastered, and the roof is composed of sandwich panels. There is a stand with 2 rows of seating along one wall.
According to the mayor of Velka Bystrice Marek Pazdera, the sports hall forms an integral aspect of the town.
“The sports hall was built in 2006. We decided to invest in this project because there was a need to have a municipal sports hall which can serve for PE school lessons, as well as for after school clubs’ activities and for different local sports associations trainings.”
Meeting Czech acoustic legislation
The standard ČSN 73 0527 (Acoustics-Acoustical design of rooms – Rooms for cultural uses – Rooms in schools – Rooms for public purposes) sets RT values from 250 to 2000 Hz for sports hall according to the volume of the room. The standard requirements must be fulfilled by all newly built and reconstructed buildings.
Compliance with the legislation is controlled by the authority of Ministry of Health called “Hygienic station“. Originally there was an unfortunate mistake by the control authority and the building was approved for operation despite the missing acoustic treatment.
“Over time when the space was being used it turned out that teachers and trainers were not heard properly. Pupils and students could not understand speech well. There were too long reverberations. I got many complaints about the acoustics from visitors, so I decided to find a solution and change the acoustic comfort in the hall, which meant further investment“, the mayor continues.
Measuring the acoustics
All measurements were done by a neutral third party acoustic consultant, Akusting and made according to Czech acoustics standards which ensure high quality acoustics in public buildings.
Measurements revealed that the hall was far below what the building code required, with extremely long reverberation time values ranging from 4.35-6.78 seconds range of frequencies most relevant for speech. To put into context, the target value for reverberation depends on the room volume and the optimal value for a room this size should have been under 2 seconds.
Much work was needed to bring these values down into the optimal range.
Improving the acoustics with sound absorption
Sound absorbing materials were the only solution. The acoustic absorber Ecophon Super G™ Plus was chosen for this space because of its impact resistant properties. The panels had to be installed in rows because of trusses in the ceiling. The rest of the ceiling was covered with plasterboard to create a unified surface.
It is important to remember that this was an additional installation, which incurs additional problems such as the need to closing the space for the duration of the reconstruction and protect surfaces such as the floor in order to avoid damages. Such inconveniences are typical for situations demanding additional acoustic treatments after the building process is already complete, which is why it is better to do it right the first time.
A sound effect on people
The expected noise reduction as a consequence of this treatment is estimated to be about 3.5dB, a halving of the sound energy in the room. A post-occupancy evaluation revealed that the users of this space found the acoustics to be greatly improved. The incredible difference before and after sound absorbing materials were installed can be clearly heard in the videos below.
Before acoustic treatment:
After acoustic treatment:
Watch the full case video about the renovation: