23 Aug The Realm of Effective Acoustics Part 1: Sound Isolation Vs Room Acoustics
Enter the realm of effective acoustics. Here we dispel common misconceptions and take a look at the proper way to solve problems related to noise and sound, from making a room sound better to controlling and measuring noise.
The Armchair Acoustician
You’re at a party. You’re enjoying a drink as you mingle among amiable guests. Suddenly, the conversation turns. The new topic? Sound and noise. You find yourself in the presence of an armchair acoustician.
You know you’re dealing with an armchair acoustician because they have a tidy solution to any problem related to noise or sound:
- Noisy upstairs neighbours? They must’ve installed hardwood floors. Add soundproof panels to your ceiling!
- Kids making a ruckus downstairs? Install carpet in the basement to absorb the noise!
- Concert too loud? Measure the noise levels with this handy app, then call the police!
- Lacklustre-sounding stereo? Try these super expensive cables. It will sound AWESOME!
The armchair acoustician means well, but their advice is often a mish-mash of marketing maxims, acoustical myths, and misinterpreted ideas passed along by other armchair acousticians.
Let’s clear up the misconceptions and discuss some of the science behind noise and sound. This post looks at the differences between sound isolation and room acoustics, and how flooring types and acoustical treatments affect how we experience noise.
Sound Isolation Vs. Room Acoustics
Many armchair acousticians recommend removing or installing sound absorptive material (such as acoustical panels, curtains, or carpet) as a way of isolating sound. The truth is that acoustically absorptive materials simply do not add to sound isolation in a meaningful way.
Reverberation and Room Acoustics
You may have had experiences that suggest noise can be controlled with absorptive surfaces—the armchair acoustician surely has! But consider the basement carpet example: Without carpet, the noise within the basement might be bit louder because the space is more reverberant. This means the echoic conditions amplify the build-up of sound.
Imagine what would it sound like if you were to shout in a carpet store? Compare that to a cathedral? (I recommend asking permission before testing this in the real world) Or strum an electric guitar without an amplifier and compare that to an acoustic guitar. Your shout and strum occur at the same loudness in both settings, but you perceive one to be louder because of the reverberant conditions. Sound builds up more in a cathedral or the body of an acoustic guitar. Without a hollow, reverberant body, an electric guitar strum sounds quieter. And your shout at a carpet store might sound like it was swallowed by a woollen sock.
When comes to sound isolation, the factors that affect room acoustics—such as reverberation—don’t necessarily affect sound isolation, which is determined by a partition’s ability to limit noise transmission. Consider the following:
A noise downstairs – B sound isolation = C sound level upstairs
What this means is that a loud noise downstairs is going to be loud upstairs unless sound isolation is changed. This happens at the separation, i.e., a wall or ceiling/floor assembly. Modifying the room acoustics of a downstairs space may end up increasing A without affecting B. In other words, the physical property of sound isolation between the two rooms stays the same, carpet or no carpet. Unless the change in reverberant conditions is absolutely drastic (which, in a residential setting, never happens), the difference between A and C isn’t noticeable. The only effective way to improve sound isolation is to add mass to the separation—and that’s what we professionals are here for!
If you are looking for proven acoustical solutions, give us a call! Our team of acoustical professionals has the knowledge, experience, and instruments to address your noise-related issues.
In Part 2 we will dig deeper into sound isolation and room acoustics, and also examine what happens when the armchair acoustician goes viral. In the meantime, if you have any questions about acoustical myths, please post them in the comment section below.
Written by Joonas Niinivaara