Colorfully illuminated PLEXIGLAS® sound panels

© Lichtobjekte estol GmbH

Illuminated acoustics miracle

At concerts, nothing is more important than great sound quality. In the Landesfunkhaus of the Norddeutscher Rundfunk in Hanover (State Broadcasting Station of the public broadcaster Norddeutscher Rundfunk), PLEXIGLAS® sound panels improve the acoustics and simultaneously characterize the stage design.

The radio philharmonic of the public broadcaster Norddeutscher Rundfunk (NDR) plays almost daily in the large broadcast hall of the broadcasting station. However, the hexagonal shape of the room and the intricately structured ceiling make good acoustics difficult to achieve. The solution was to install sound steering elements, so-called sound panels, made from PLEXIGLAS® on the ceiling. These not only ensure great acoustics in the hall, but also look great thanks to their integrated lighting.

Complicated conditions

No two concerts are the same, but every concert relies on great acoustics. However, when there are up to 140 musicians on the stage and 1,200 people in the audience, as well as different conditions at each concert, it is very difficult to ensure that the sound is always excellent. The large broadcasting hall in the Landesfunkhaus in Hanover is a listed building, which, in addition to the hexagonal form of the room and the intricate ceiling cladding made of plywood panels, makes it difficult to ensure good acoustics. “It takes a while for the sound to travel across the room which made it difficult for the musicians to play synchronously,” explains Michael Lahme, Managing Director at Lichtobjekte estol GmbH and technical developer of the sound panels. “The Landesfunkhaus came to us with the request to develop a sort of artificial ceiling to improve the acoustics.”

Flexibly adjustable panels

This meant that the technical developers at estol faced a brand new challenge: “Normally, individual lighting is the main focus of our projects,” says Lahme. “We have already developed some lighting elements which absorb sounds.” However, the application in the Landesfunkhaus in Hanover required sound to be reflected and scattered in such a manner that it was perfectly timed for both the musicians and the audience. Furthermore, the sound panels needed to enhance the visuals of the stage, not disrupt them.

Precisely shaped

PLEXIGLAS® LED was the perfect material for our plans.

Michael Lahme
Managing Director at Lichtobjekte estol GmbH

“For this task, we needed a really hard material, as higher density materials reflect the low tones from the instruments better. The material also had to be able to channel light across large surfaces,” explains Lahme. “We already knew PLEXIGLAS® LED from other projects. Thanks to its dual-sided edge lighting, it was perfect for our plans.” The low material weight and the excellent plasticity of the brand acrylic glass from Evonik were additional reasons for its selection. Sound usually emanates symmetrically from its source. However, sound waves can be reflected or broken if they contact a surface which resists them. To ensure the sound reaches the orchestra members and the audience as desired, 16 PLEXIGLAS® LED sheets were molded into a concave form by the Firma Kreideweiss GmbH and glued using ACRIFIX® before they were attached above the stage by three cables.

Individually adjustable sound panels

PLEXIGLAS® as an acoustics miracle

In order to find the optimum positions for the panels, the musicians took part in a two-day session during which different scenarios were enacted and the sound propagation was measured. Now the sound panels can be adjusted for every concert via touch operated control panels.

Depending on the number of musicians on stage, the sound propagates through the room in different manners, thus requiring adjustments to ensure the best possible sound propagation. Seven of the panels are therefore mounted in place, however the height and angle of nine further panels can be adjusted, thus enabling adjustments to be carried out for individual scenarios, such as a full orchestra, solo acts or a chamber orchestra. “The panels can be individually adjusted depending on the number and position of the musicians on stage,” says Lahme. “They are therefore significantly more flexible than a solid ceiling.“

An illuminated eye catcher

The illumination of the PLEXIGLAS® panels in up to 16 million colors immerses every stage in a sea of colors.

Michael Lahme
Managing Director at Lichtobjekte estol GmbH

The panels also enhance the large broadcasting hall from an aesthetic perspective: They can be illuminated, assume the function of ceiling lights and ensure optimal lighting on stage. The panels use high-output RGB LEDs which illuminate the PLEXIGLAS® LED sheets from two edges. “Thanks to the excellent photoconductivity of PLEXIGLAS®, the light is directed evenly across the whole area of the panel,” explains Lahme. “This creates an elegant illuminated object, which can shine in up to 16 million colors.” This means that the PLEXIGLAS® sound panels not only guarantee excellent acoustics in the large broadcasting hall, but also create the perfect mood lighting as well.