Last updated: May 17, 2022 at 14:59 pm
If you’re planning on moving to a flat and are worried about neighbour noise, or if you’re concerned your new tv, sound system or games might cause a noise nuisance, you may have wondered whether sound travels up or down. If you can only afford to focus your soundproofing efforts in one direction, which is best?
In short, sound can travel in all directions meaning it is omnidirectional. The direction it moves depends on various factors.
IN THIS ARTICLE
What Is Sound?
To understand how sound moves, first, you need to understand what it is. When something makes a sound, it vibrates. This vibration causes it to knock against air molecules which begin to vibrate too. These vibrations move in a wave until they run out of energy. If we are close enough to hear the sound, the wave hits our ear and travels to our eardrum, which begins to vibrate too. This vibration is translated as sound by our brain.
Sound can travel through any medium, air, liquid or solid. How well it travels depends on the density. For example, you’ll have noticed you can hear sounds underwater, but they’re very muffled. It travels through the air much more easily s.
How far the wave moves (how far away you can hear it) depends on a few factors. The first is the initial vibration that caused the sound; the bigger the impact, the more the vibration and the farther the wave will travel.
The frequency also affects the wave’s power; low-frequency sounds tend to travel further. Finally, it depends on how many objects the wave must travel through. As a sound wave passes through walls, windows, trees, fences, etc., it loses some of its power. Therefore, when you complete a soundproofing project, the more mass you can add, the better the result will be.
How Sound Travels
When you live in a flat and can hear everything your upstairs neighbour is doing, it’s easy to believe sound moves in a particular direction, from upstairs down to you. However, if you think about it, that’s not the way sound works.
If you have the radio playing in a room, you can hear it wherever you are. If sound moved in one direction, only someone standing in front of the radio would be hit by the sound wave and be able to hear it. That isn’t what happens.
Sound moves in all directions, and the word for this is omnidirectional. It’s true that the sound will be loudest in the direction the sound is pointed toward, but you’ll still hear it elsewhere. This is a good thing; it would make having a conversation significantly more difficult if you always had to be standing directly in front of the person talking to you!
Another factor that affects a sound’s travels is echoes. Depending on how many soft furnishings the room has, how big the space is, etc., sound waves can bounce off the walls and ceiling, causing an echo. An echo can make a noise seem much louder than it really is and mask the sound’s source.
Why Are Some Noises Louder Than Others?
As explained above, a significant component in the amount of sound we can hear is frequency. Low frequency sounds travel further. That’s why you might not be able to hear the music your neighbour is playing, just the booming of the bass.
The music is a high-frequency, and the wave runs out of power before it reaches you. The bass is low-frequency, and so it travels further.
As well as the frequency, the type of noise is a major factor. There are two main types of noise, airborne noise and impact noise. As the name suggests, airborne noise is caused by vibrations in the air and travels in a wave to reach our ears. Examples of this are talking, music, the tv, using a vacuum cleaner, etc.
Unless your walls or ceiling are incredibly thick, it’s likely you’ll be able to hear some noise from your neighbour, even in a semi-detached house. So long as your neighbours are considerate, however, this noise should not be loud enough to be a nuisance.
On the other hand, if the walls are thin, then it’s possible that even normal day-to-day noise could be intrusive. In this case, you would need to look at adding mass to the walls to restore peace and quiet. If the noise is annoying you, it’s likely your noise might be irritating your neighbour too. Consider having a friendly chat and see if you can share the cost of fitting some extra soundproofing.
Impact noise is caused by something hitting something else. In a flat, the classic example is the sound of your upstairs neighbour’s feet hitting their floor. The impact causes the floor to vibrate, and this vibration travels through the floor to the joist’s underneath. From there, it travels to your ceiling, and if your ceiling and walls are not decoupled, it can travel down your walls too.
This method of transmission, combined with the fact that impact noise is a low-frequency sound, means that impact noise from above is often a significant problem in blocks of flats. Laying carpets or thick rugs helps muffle the sound. For this reason, some buildings have a no wood floors covenant that potential owners or renter must agree to protect other residents.
What Can You Do to Reduce the Noise in Your Home?
The first thing to do is ascertain the type of noise that’s bothering you, impact or airborne, and where it’s coming from. That will allow you to focus your efforts in the right area. However, sound can travel in all directions and get in through any gap, so completely soundproofing the rooms where you can hear the noise is best.
The critical components in reducing sound entering your home are adding more mass and sealing up any gaps. Check out this handy guide to soundproofing an entire room, including the ceiling and windows. There are options for every surface and every budget, so you will be able to find a solution that works for you.