Acoustic Performance of Sound Absorbing Materials Produced from Wool of Local Mountain Sheep

Katarzyna Kobiela-Mendrek, Marcin Bączek, Jan Broda, Monika Rom, Ingvild Espelien and Ingun Klepp


Wool of mountain sheep, treated nowadays as a waste or troublesome byproduct of sheep husbandry, was used for the production of sound-absorbing materials. Felts of two different thicknesses were produced from loose fibres. Additionally, two types of yarn,ring-spun and core rug, were obtained. The yarns were used for the production of tufted fabric with cut and loop piles. During the examinations, basic parameters of the obtained materials were determined. Then, according to standard procedure with the use of impedance tube, the sound absorption coefficient was measured, and the noise reduction coefficient (NRC) was calculated. It was revealed that felt produced from coarse wool exhibits high porosity, and its sound-absorbing capacity is strongly related to the felt thickness. For thicker felt the NRC achieved0.4, which is comparable with the NRC of commercial ceiling tiles. It was shown that the crucial parameter influencing the sound absorption of the tufted fabrics was the pile height. For both types of yarns, when the height of the pile was increased from 12 to 16 mm, the NRC increased from 0.4 to 0.42. The manufactured materials made from local wool possess good absorption capacity, similar to commercial products usually made from more expensive wool types. The materials look nice and can be used for noise reduction as inner acoustic screens, panels, or carpets.

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WOOLUME: Mapping the market for acoustic and sound absorbing products made of wool

Anna Schytte Sigaard and Vilde Haugrønning


This report is the first deliverable from work package 2 of the WOOLUME project. The main goal of WOOLUME is to
explore different ways of using wool from Polish Mountain Sheep to achieve better utilisation of resources and value
creation. The aim of the report has been to map the market for acoustic and sound absorbing products made of wool to
examine the potential to introduce coarse wool as a material. This has been done through desktop research and
interviews with a focus on the qualities of wool as a natural product. Findings show that though man-made materials
dominate the market for acoustic products due to lower prices, wool is preferred as a material due to its natural
properties as well as aesthetics. Producers using wool consider their products to be high-end, intended for people who
want very good quality products and who are willing to pay a higher price to achieve this. However, few producers use
coarse wool in these products, and many are made of pure Merino wool. Using Merino wool which is often considered
of very fine quality due to the low micron-count does not correspond with the ideal of good utilisation of resources.
Therefore, we are proposing to utilise coarse wool which today is discarded as a mere by-product to meat-production.
Merino could instead be used for products where fineness and softness are important factors such as for clothing. In
addition, we argue for the rawness and uniqueness of the look of coarse wool as positive in terms of aesthetics and as
something that adds to the position of acoustic products made of wool as high-end.

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