Acoustic cloth and standards: workability

Which standards and certifications provide meaningful insight into the quality, practical usability, and performance of a speaker fabric? The second part of our blog series “Acoustic fabric and standards” focuses on the parameters that allow a reliable assessment of the workability of speaker cloth.
 

Which parameters and standards define workability?

A speaker fabric must meet high expectations not only in terms of sound transparency. It should also ensure that speaker fronts, acoustically effective wall coverings, ceiling panels, and AV furniture look as refined as possible, while protecting the technology behind them from dust, particles, and contact. This requires a material that is both easy to work with and sufficiently durable.
 

A key factor: elasticity in acoustic fabrics

Elasticity, or stretchability, plays a particularly important role in these applications. The more elastic a fabric, the easier it can be mounted with the right level of tension, for example on a frame. Single jersey fabrics offer a clear advantage over woven or braided materials, which are often found on vintage radios or older loudspeaker fronts. Today, such materials are mainly limited to niche uses, such as the fronts of certain instrument amplifiers. In these cases, aesthetic conventions often seem to matter more than practical considerations. Anyone who has worked with such rigid materials will be familiar with their limitations in processing.

Woven fabrics can be made more elastic by adding elastane fibres, as is common in modern denim. Classic denim is highly durable but almost entirely non-stretch. A close-fitting pair of jeans would not be possible without elastane. However, this comes at the expense of long-term stability, as elastane tends to lose its elasticity over time. The result is a fabric that gradually loses its shape and resilience. For this reason, blended fabrics containing elastane are generally not suitable for acoustic applications. A speaker covering that begins to sag after a few years is hardly desirable.

The solution lies in single jersey construction. Similar to a knitted jumper, stable yarns are formed into an inherently elastic structure, allowing the fabric to stretch without the need for additional materials. It stretches well in length, and even more across the width. We discuss the advantages of avoiding material blends in more detail in our article on the recyclability of acoustic fabrics.

Elasticity is expressed as a percentage, indicating how far a fabric can stretch from its original dimensions and return to its initial shape. The standard fabric from Akustikstoff.com offers 32% elasticity in length and 62% in width. In practical terms, this allows for a wide range of tension during installation. The fabric can be mounted securely, and pulled smoothly around edges and corners without forming creases or bulges.
 

When does an acoustic fabric fail?

Bursting strength is another key parameter for assessing both workability and durability. Measured in kilopascals (kPa), it indicates the maximum pressure a material can withstand before it ruptures. This value is essential when evaluating textiles that are subject to mechanical stress.

Various testing methods are used to determine bursting strength. These simulate real-world conditions by gradually increasing pressure until the material fails. This allows for precise identification of the breaking point and provides a reliable assessment of strength under realistic conditions.

ISO 13938 defines several standardised methods for these tests, which are an integral part of textile quality assurance. One commonly used approach is the pneumatic test. Particularly suitable for lightweight and elastic fabrics, it stretches the material using air pressure until it fails. The results vary depending on the material. Lightweight fabrics such as summer clothing, underwear, or fine jersey typically fail between 100 and 300 kPa. Medium-weight fabrics for T-shirts and jumpers often reach 300 to 600 kPa. More robust textiles such as denim, jackets, or workwear range from 500 to over 1,000 kPa. The fabrics from Akustikstoff.com achieve values above 500 kPa, which is a notable level of bursting strength for a lightweight jersey fabric.

This concludes part two of our blog series on standards and testing methods for speaker textiles. In the next article, we will look at the protective properties of acoustic fabrics.