How does one stop low frequency issues in a small room? The short answer is that one does not stop low frequency or bass issues in small room acoustics. The best we can hope for from an acoustical design perspective is for minimization of the major issues and some patience and toleration of the others. The reason for this is basic physics.
A 40 Hz. wave is how long? A 40 Hz. wavelength can be found by dividing the speed of sound in feet which is 1,130 feet / second by the frequency we need to find the length of. Dividing 1,130 by 40 produces a quotient of around 28 feet. Therefore, a 40 Hz. wave is 28 feet long.
If we wanted to be absolutely sure acoustically, we need a room at least 28 feet long in every dimension in order to not have this long, low frequency wave cause any acoustical issues at our listening position. Unfortunately, real estate is expensive and having a room with a 28′ length, width, or height is a rarity. We need a powerful “sponge” to deal with these low frequency wavelengths.
Current low frequency products in the marketplace do not work for many reasons. Sometimes, a low frequency or “bass” absorber is an afterthought to an existing companies product line. They spent their monies on middle and high frequency control and left the more difficult design issues of low frequency absorption on the sideline.
Since they are marketing absorption panels, they need a bass absorber to round out their product line. I have seen companies even raise the definition of low frequency control to match their products poor absorbing performance. Some companies consider low frequency absorption to be at 400 Hz. Really?
Most low frequency absorbers simply don’t cut it
Most low frequency absorbers in the market place can be thrown over your shoulder and carried out of the room. How does one absorb enough low frequency energy to have a sonic impact in their products if one can carry it out by hand. How does one absorb parts of a 28′ long wave with a hand held device. The answer is you don’t.
One can change the design absorption frequency to match what the product actually absorbs at and call it a low frequency absorber, but the reality is that it is not a low frequency absorber. It is only marketing jargon that the uninformed will buy into and eventually purchase. after a brief period of use, they will still have low frequency issues.
Address the energy that falls below 100 Hz
Low frequency energy control requires a design parameter that addresses low frequency energy that falls below 100 Hz. It must have this design criteria firmly in line and focus if it is going to create a product that actually absorbs below 100 Hz. It must also absorb at a high rate and level at the most problematic frequencies found in most rooms.
These are the low frequencies that fall from 30 Hz. – 50 Hz. One can not absorb effectively at these frequencies with a product that is lightweight and small. The laws of physics will not allow for this no matter what the companies sale literature says.