Answering questions about acoustics and audio-visual systems is one of the things that we at AVANT ACOUSTICS love to do! We would like to share a few answers to acoustical questions that come up rather often. If you have any questions, please pick up a phone and call. One of us would love to talk about our favorite subject!

Can I paint my acoustical panels?

That depends. Most sound-absorbing panels work by transferring sound energy to change into heat by passing through tiny spaces between fibers (fiberglass, Tectum), between small particles (acoustical plaster), or through small holes (microperforated panels).

First, determine your type of panel. Then, evaluate if painting will seal up the tiny spaces or holes required to absorb sound. In many cases, a thin coat of spray-applied paint will not adversely affect panel performance, but paint applied more thickly with a brush or roller will reduce the panel’s ability to absorb sound, especially at high frequencies. When in doubt, check with your panel manufacturer.

Do acoustical panels keep sound from coming through walls?

No, acoustical wall panels typically will not do this.  The best solutions in these cases are to fill any penetrations, make gaps airtight, and make walls more massive.

How many acoustical panels do I need in my space?

That depends on several factors, including room geometry, surface materials, construction, and the intended use of your space. There isn’t really a one size fits all answer for this question, especially for irregularly shaped rooms. That’s when an acoustical consultant can help.

I need less sound transmission. Can’t I just add some insulation?

Again, that depends. Insulation is a good sound-absorber because it is porous, but that makes it less effective at blocking sound that travels between two spaces. The best way to block sound is with massive, dense, and limp materials. Thus, if you want to keep rain noise from coming through a metal roof, gluing some insulation under the roof might not make a significant improvement.

However, insulation can help reduce noise transmission in these two ways:

1. Significant amounts of insulation can reduce sound levels in a noisy room so that there is less noise to transmit to an adjacent room. This can be helpful in noisy mechanical rooms.
2. It helps if it is between layers of dense materials, like a metal roof and a gypsum board ceiling. In that case, the insulation helps reduce resonance in the cavity between the two layers, and improves the sound-blocking performance of the whole construction.

There’s not that much difference between 80 and 90 decibels (dB), right?

Wrong! 90 dB actually sounds about twice as loud as 80 dB! Because of the sensitivity of our ears, sound is measured on a logarithmic scale, not a linear scale. Practically speaking this means that most people would notice a change of 2-3 dB but not consider it significant; a change of 6-7 dB is significant and a change of 10 dB is twice or half as loud. This applies to direct sound levels, of course, but it also applies to many other measures related to acoustics:

• STC – Sound Transmission Class – Partition isolation
• OITC – Outdoor Indoor Transmission Class – Exterior isolation
• NIC – Noise Isolation Class – Field-tested partition isolation
• CAC – Ceiling Attenuation Class – Sound attenuation of lay-in ceiling constructions
• IIC – Impact Isolation Class – Isolation of impact noise in roof/ceiling/floor construction
• NC – Noise Criteria – Sound levels generated by mechanical systems

So remember that logarithmic scale when evaluating two partition constructions or evaluating noise generated by mechanical diffusers.