Sound Proof Insulation - Experimental Samples

There are now several ways to soundproof a wall and insulate it. Improvements in the soundproofing industry have resulted in products that are now more effective and cost less than the old traditional ways in soundproofing methods. Soundproof insulation had come a long way.

Some principles

However, one must understand some of the main principles of sound movements and how to minimize or totally eliminate it. Some of these include getting the information that the effect of insulation is minimal in both low and high frequencies.

In a conventional wall, the effects of insulation are very similar to having insulation. The largest gains are just above the primary low-frequency resonance, low frequency gains are non-existent and high frequency gains are very minimal.

More experiments

The effects of adding layers to a normal single wood stud wall results in having the gains in the midrange higher at middle and high frequencies. Low frequencies, however, the performance is not as good as with the lighter installation.

Here the STC rises by a mere 2 points (from 32 to 34). Insulation has much more value in decoupled walls.

In walls having mechanical connections between the two sides, the insulation has proven the benefits of insulation at middle and high frequencies. In low frequencies, however, the capacity of the insulating materials to absorb sound falls dramatically. The benefit of insulation at low frequencies is to lower resonance points.

Still, lowering the resonance is valuable and in walls with damping or decoupling, the insulation has considerable value at middle and high frequencies which should be considered mandatory for any sound isolation application.

As a sample on how insulation becomes less effective as frequency falls, place a fiberglass in front of the mid and high frequency speakers in your room and listen to what happens. The sound would probably be muffled and muted.

Now put the same fiberglass in front of the subwoofer cones. Nothing happens. This is the same with the walls.

STC

Dealing with sound, one needs to be familiar about STC ratings, or the sound transmission class ratings. STC ratings measure how much a particular sound proofing construction material reduces sound.  (R-values in thermal insulation are the values of retained heat in the materials used.)

Higher STC rating indicates that the materials used are better at noise reduction. A wall with an STC rating of 30 will allow most sentences to be heard clearly in a conversation. A wall having an STC rating of 50 will block most of the loud speech and only transfer faint sounds of loud musical instruments. 

Tips

Most often, people thought using denser insulation materials cures every sound problem. Generally, it is preferable to use standard building type insulations (like fiberglass).

It is not desirable to use expensive and very dense insulations. In addition to the expense, they also tend to make low frequency performance worse by raising the resonance frequencies.

Some notes

The use of sound proof insulation is critical and valuable, but insulation alone doesn’t win, especially in conventional walls where direct structural connections exist between the sides.