How to Test an Acoustically Transparent Fabric?

What is an acoustically transparent fabric and how do we test them?

There are many types of fabric that we can buy from our local upholstery shop, but how do we know what type of fabric to use if we want to build an acoustic panel?

In this article, we attempt to discuss the types of acoustically transparent fabric, what signature they will have on sound, and also other requirements if they are to be installed in a commercial space to meet fire-safety standards.

Why is it important to use an acoustically transparent fabric?

An acoustically transparent fabric is one that allows sound to pass through without much barrier. This is important because we want the sound to pass through the fabric to be absorbed by the sound-absorbing substrate filled in the acoustic panel, for example, acoustic foam or fibreglass wool.

We do not want the sound to bounce back into the room once it touches the fabric, because it would not get absorbed by the insulation behind. There are many types of fabric that fall into the category of being acoustically transparent. We will discuss below on how to test for them.

How to test if the fabric is acoustically transparent?

There are 3 ways to test for an acoustically transparent fabric. Let’s see what they are below!

Breathe Test

The breathe test is simple test that you can do anywhere. Just put the fabric against your nose and see if you can comfortably breathe through it! The easier you can breathe through the fabric, the more acoustically transparent the fabric.

Light Test

Another simple test is the light test. Simply put the fabric against a bright source of light (e.g. the florescent lamp on your ceiling) and determine if you can see the light from behind the fabric. The more light that peers through, the more transparent the fabric.

Lab Test

To properly determine if a fabric is acoustically transparent, we can always request for a lab test of the acoustic signature of the fabric. Unfortunately, most fabric vendors do not perform this test. But fear not! Because we know how to find out for ourselves.

What fabrics are definitely not acoustically transparent?

Examples of fabric that are not acoustically transparent are:

  1. Leather
  2. Faux leather made from polyester
  3. Polyester or polymer-derived fabric that is more than 1mm thick
  4. Any fabric that is thick and has high thread-count
  5. Homogenous man-made fabric with no weaves

The list is not exhaustive but you would notice that they generally have tight weave and high resistance to airflow. If you have a fabric that has the above characteristics, you would know to avoid them for acoustic panels!