Acoustic test rooms

Asymmetrical Structured Absorber
© Fraunhofer IBP
Asymmetrical Structured Absorber ASA

Continuous improvements in product quality through testing in modern acoustic test rooms#

More and more importance is being placed on acoustic properties when developing high-quality products. For this reason, industry continuously tests and optimizes the acoustics of its products, while also taking into account their compliance with relevant legal regulations. Since many years, our experts have been helping customers to design and build first-class acoustic measurement environments and test rooms.

Development of absorber systems for acoustic test rooms

As a lining for anechoic chambers, current standards (ISO 3745 & ISO 26101) and popular doctrines require an even distribution of λ/4-deep wedges in fibrous / porous material with an absorption rate of 99 percent at a vertical sound incidence. On average, however, this takes up one third of the total volume of the chamber.

With this in mind, in recent years we have developed various technologies and lining systems that offer considerable space savings in test rooms compared to systems with a similar acoustic performance.

  •     Composite panel resonator
  •     Broadband compact absorber
  •     Asymmetric structure absorber

The application of the broadband compact absorber technology is particularly suitable for a wide range of acoustic measuring rooms and wind tunnel plenums where anechoic characteristics are required.

Investigation of sound-absorbing materials and structures

To develop sound-absorbing wall linings, we perform measurement-based tests on materials and structures. These include

  • absorption measurements with a vertical sound incidence in impedance channels and Kundt’s tubes with different dimensions according to DIN EN ISO 10534-2
  • absorption measurements with a diffuse sound incidence in the reverberation chamber according to DIN EN ISO 354.

Simulation and design of anechoic chambers

The quality of an anechoic or semi-anechoic chamber not only depends on the capacity of the lining to absorb sound but also on other parameters, such as the shape of the chamber and the position of sources of noise and receivers. When planning new anechoic chambers, it is therefore essential to optimize all relevant parameters. For this purpose, we have developed a calculation tool to predict anechoic conditions on virtual measuring paths inside the chamber.

Acceptance tests for anechoic chambers

We verify the suitability of anechoic chambers by measuring the reduction in sound pressure levels according to ISO 3745 or ISO 26101 with pure tones or third-octave noise. In this context, we offer measurement-based studies and acceptance tests for anechoic chambers as a service to our customers to support their development processes.

Design and optimization of aero-acoustic wind tunnels

When designing new aero-acoustic wind tunnels, the sound-absorbing technologies developed by our experts can also be implemented in deflection elbows in baffle silencers. The minimal pressure loss achieved with this combination enables low-noise wind tunnels to be realized. We offer appropriate development services related to the design and optimization of aero-acoustic wind tunnels.