Acoustic Curtains – Sound Absorption

Acoustic curtains are essentially sound absorbers and are used for control of reverberation (unwanted echo). Acoustic curtains can be installed as static elements or tracked to allow for adjustment of absorption and exposure of a reflective surface behind.

Positioning, fabric weight, weave and fullness as well as spacing from reflective surfaces all effect absorption efficiency. Typically medium to heavy weight fabrics such as wool and velvet are preferred. Acoustic curtains are generally headed at 100% fullness (and sometimes 50%). It should also be noted that acoustic curtains are more effective within a certain frequency range; typically 500 -2000Hz (peaking at around 1000Hz). Published information typically give the following absorption coefficients (α):

Fabric Weight 480 – 500gsm, Curtain at 100% Fullness

Frequency α *
125Hz 0.07
250Hz 0.31
500Hz 0.49
1000Hz 0.75
2000Hz 0.70
4000Hz 0.60

Fabric Weight 630 – 650gsm, Curtain at 100% Fullness

Frequency α *
125Hz 0.14
250Hz 0.35
500Hz 0.55
1000Hz 0.77
2000Hz 0.70
4000Hz 0.60

* The figures given above are indicative only and application of such figures is not covered on this page.

Acoustic Curtains – Sound Transmission

Acoustic curtains are not generally used to stop noise transmission; for effective noise barriers a building solution is usually required.

However, in some circumstances with careful planning, acoustic curtains can offer some degree of sound transmission loss. Limp high mass fabrics (barium sulphate loaded vinyl etc) are generally used (with a separate face fabric if required). The effectiveness of such curtains / drapes is dependent on good sealing and the nature of the walls, ceiling and floor construction of the surrounding area (i.e. do they “leak” sound or offer flanking paths around each other and the curtain / drape).