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Improvement of room acoustics by activating floor coverings as resonance absorbers with textile spring systems (textile spring system)

The aim of the research project was to acoustically activate a plain floor covering, such as a design covering, to improve the room acoustics in the range of speech frequencies. For this purpose, several resonance frequencies were to be realized in this frequency range by a substructure with different dynamic spring stiffnesses according to the principle of the plate resonator.

The approach of this research project was to realize this sophisticated spring system by a tufted textile structure. In addition to different spring stiffnesses, a support structure was also implemented to meet the mechanical requirements of the plain floor covering. The support structure was implemented using the wide range of patterning possibilities offered by tufting technology.

New testing technology visualizes the acoustic properties:

As part of the project, an acoustic camera was also acquired for the TFI. This was intended to visualize the spatial resolution and the influence of furniture on the behaviour of the resonance absorber.

The picture shows as an example an image of the acoustic camera user interface, where a measurement was taken in the impedance tube. The coloured dot visualizes the area of sound reflection on the level of the specimen. The bar diagram in the right half of the image shows the sound intensity as a function of frequency (one-third octave bands) for the point marked in the crosshairs (left half of the image).

Screenshot of a measurement with the acoustic camera


In addition to laboratory tests on small-format specimens (20 cm x 20 cm), measurements were carried out in the reverberation room with an area of 12 m². All measurements showed the characteristic curve of a resonant absorber with a pronounced, narrow maximum. The measurement results confirmed the approach of the research project. In the further course of the project, the effective frequency range of the resonance absorber was extended by a second, adjusted spring structure.

The figure shows the sound absorption coefficient vs. the frequency. In each case, the difference between measurements of different floor coverings with and without textile spring underlay is shown. In the case of the laminate, the behaviour of two different textile spring underlays was also analysed.

Sound absorption coefficient as a function of frequency for different floor covering and textile spring systems

Funding program and project number

IGF 20728 N/1


01.06.2019 – 31.05.2021


Project partners and/or other research institutes


The IGF project “Improvement of room acoustics by activating floor coverings as resonance absorbers with textile spring systems (Textile Spring System)” IGF 20728 N/1 of the Research Association Forschungskuratorium Textil e.V., Reinhardtstraße 14 – 16, 10117 Berlin was funded by the Federal Ministry of Economic Affairs and Climate Action via the AiF within the framework of the program for the promotion of joint industrial research and development (IGF) on the basis of a decision by the German Bundestag.

The report on the research project can be requested as TFI publication series No. 2021/117.


Christian Goetz

Phone: +49 241 9679-160