I’ve often found that the biggest threat to soundproofing solutions in apartment buildings comes from shared walls. But does that mean that you should neglect the floors and ceilings? Today, we’re going to settle the question once and for all. So let’s figure out whether sound travels up or down in an apartment building.
Well, while many people think that sound travels in one direction, that’s actually just a misconception. People imagine the waves of music that leave their speakers as going out in a straight line or in a conical shape from the speaker. But in order to have sound travel toward a particular area, you’d have to physically direct it. The best way to do that is to use something like a tube or a cone — which is why we have megaphones.
Still, most people aren’t directing the noise they make in their own home. They’re just walking around their apartments, watching movies, and living their lives as usual. So where does all that sound go? Well, if we want to understand the direction of sound, we first need to know how it’s dispersed.
How Sound Travels
Understanding the various types of noises is the first step to being able to defend against them. That’s why I always recommend reading my article on impact and airborne noise before embarking on your first soundproofing project.
You see, when you’re trying to figure out where noise goes after leaving its source, you have to keep in mind its mode of transportation as well. How sound travels is a much more important question here.
Imagine, if you will, setting up a speaker system on the floor of your apartment and playing your music with the bass turned down low. If your neighbors could hear it, that would mean that the noise was traveling through the air. As scores of science fiction movies keep telling us, sound can’t exist in a vacuum. So no air, no sound.
If I were to recommend a soundproofing solution to prevent this type of noise from seeping out of your apartment, my first suggestion would be to plug all of the holes in walls, ceilings, and floors. However, there is an even more persistent type of noise.
If you were to turn up the bass dial on your speaker, you might start to feel the floor shake a little bit. Because this type of sound travels through the building structure, we usually call it structure-borne noise — or impact noise. This is why you’re particularly annoyed when your upstairs neighbor keeps stomping above your head, and you can feel the building trembling because a bus just shuffled past it.
Although most airborne noise isn’t able to carry through solid floors and ceilings, lower bass frequencies might. Ultimately, floors and ceilings are thicker and denser than walls, so they won’t let the higher frequency sounds through as easily.
The Positioning of the Source of Sound
The other important factor to keep in mind when thinking about the direction of sound is the positioning of the device that’s making it. If you were looking to lessen the amount of noise that passes through your walls, whether through the air or the structure of the building, you may want to move the source of the sound away from more vulnerable areas. That’s why I always say to move the TV or the computer away from shared walls.
However, positioning also matters in the question we’re trying to answer today. And since gravity compels us to have all of the noise-makers in our homes connect to the floor, you could say that sound travels downward.
Let’s take speakers as an example again. If you have your speakers sitting directly on the desk, they will vibrate against it. The sound will carry through the structure of the desk, into the floor, and to the neighbors below.
However, your neighbor is unlikely to complain about this type of noise. Your footsteps are what you really should be worried about, no matter how light on your feet you think you are. If you want to make sure that you’re not bothering your downstairs neighbors, you could try out some of my floor soundproofing tips.
So in this case, it’s safe to say that noise is more likely to travel down. When is the last time you heard sounds coming from the apartment below? It’s rare, but it happens. The sound could carry up if there were fewer obstructions in the way. So you might hear something if both your windows and your downstairs neighbors’ windows were open. Impact noise could also travel up, as in the case of a passing bus.
So Does Sound Travel Up or Down in an Apartment?
The answer is as complex as the subject matter. Technically, there are certain ways to change your environment in order to point sound toward a particular area.
Generally, though, sound travels in all directions. After all, you hear your speakers even if they’re facing away from you, right? But even though that’s technically the case, you’re probably hearing more noise coming from upstairs than downstairs. Fortunately, you can fix that by implementing some simple soundproofing techniques.