The Worst Sound of All

Isn't it amazing how much sound we're bombarded with everyday? We love to find a quiet moment where we are not acoustically assaulted by people, equipment, traffic, stereos, neighbors, cell phones, and on and on. It's hard to find that quiet moment, and perhaps even harder to find that soundproof place. Sound levels are so intense that many walls and building materials just don't stop the sound satisfactorily.

Think of it. How often are you bothered by noise from the person in the room next door, even though the door's shut? Have a music student in the house? Dad like to watch movies late at night? How about the neighbors having yet another party?

How in the world do we cope? It's no wonder that Ben Affleck slept in a soundproof sensory deprivation chamber in the movie Davedevil. But of all the noise that we retreat from there's one that's the worst of all. Bass. It's the worst because it's the hardest to stop. In the acoustics industry, "bass" is known as low frequency sound. It's the boom-boom music sound you hear coming up behind you while driving. You hear it long before you see the car that's creating it. Low frequencies are the jets flying overhead if you're near a major airport.

This is the worst sound of all because it assaults from long distance. It penetrates normal building walls and ceilings. Low frequencies are the largest and generally the most powerful sound waves we come up against daily. They are hard to escape. Paradoxically, the low frequency "bass" is what is being sought more and more in home theaters, bands, and music systems. So our dilemma is only going to get worse.

The "volume" level of sound is measured in Decibels (dB). The frequency of sound (bass, midrange, treble, low notes, high notes, etc) is measured in Hertz (Hz). The sounds that are most problematic when we retreat to a place of soundproof solitude are the low frequencies below 125Hz. This is the realm of the worst sound of all.

There would seem to be a need to set standards for healthy living that describe how to insulate yourself from such noise. In fact, there is a standard that measures a structure's ability to hold back sound. It is called STC, which stands for Sound Transmission Coefficient, and is the most recognized and discussed sound isolation term in North America.

Building codes will dictate what STC level a building needs to have. A new condo, town home or apartment will have to comply to these building codes and build walls, ceilings and floors that meet these STC requirements. If this is so, how come I can hear my neighbor? Why is my new condo so noisy? After all, the structure is built to code.

The reason that new structures are still noisy is because of the STC standard itself. STC does not measure any of the worst sound of all. It stops measuring at 125Hz... exactly where the worst sound starts. So you have a high STC wall that meets code, but sounds terrible. Great.

There is a need to change this STC standard to include these low frequencies. They do this already in Europe and Australia. In the meantime, what can you do?

Look for building techniques that have been tested below 125 Hz. Good performance below 125Hz. will help you a lot. Be aware of products like resilient channel, "sound" boards, foams, tapes, clips and especially mass loaded vinyl (MLV). These products won't help you in these critical low frequencies. Consider materials that "damp" the sound vibration. These types of products are generally known as visco-elastics and are most effective with the worst sound of all.