Summary
- Room acoustics involve sound travel and interaction with a physical space.
- Sound waves reflect, absorb, or diffuse off objects in a room.
- Improve acoustics with sound absorbers, diffusers, bass traps, and strategically placed materials like fabrics and furniture.
Taking acoustics into consideration is key for creating the optimal listening environment. Here are the key facts about room acoustics and how to improve yours.
What Are Room Acoustics?
Put simply, room acoustics are how sound travels and interacts with a physical space. A great example is how when you’re in an empty room, sound echoes quite loudly, and in another room with a rug on the floor that’s full of furniture, you won’t hear much echo at all.
In a room with furniture and a rug, those objects serve to reflect, absorb, or diffuse sound in various ways.
Sound is a wave of energy moving through the medium of air. As such, it moves out spherically from the source, and when it hits an obstacle, that object will change the way the wave is moving. Three key ways that objects interact with sound waves are by reflecting them, absorbing them, and diffusing them.
Sound Reflection
Sound reflects off smooth surfaces like walls, ceilings, and floors. An extreme example of sound reflection is echo, where sound reflects off various surfaces and reaches your ears with a delay. This is why an empty room will sound so echoey—the room is full of bare, smooth surfaces for sound to bounce off.
Depending on the position of your speakers, sound will reflect from different areas of a room and at different angles, also known as modes. You can have an axial mode, where sound is bouncing between two parallel walls.
There are tangential modes, where sound is bouncing diagonally between four walls. Lastly, there are oblique modes, where sound bounces off all the walls in a room, including the floor and ceiling. Depending on the size of your room and the mode the sound is moving in, you’re going to have different experiences with sound, and echoes will sound different.
Sound Absorption
One of the solutions to intense sound reflection and echo is sound absorption. Different materials will absorb sound differently. You might notice that in rooms with carpeted floors or area rugs, you hear a lot less echo. The same goes for walk-in closets full of clothes. This is because fabric is excellent at absorbing sound.
Other materials that are good at absorbing sound include foam, mineral wool, and fiberglass, which dedicated sound absorbers are often made of.
Absorption is best for dealing with higher frequency sounds, and you can use bass traps to deal with lower frequencies too. But only using absorption treatment in a room will make audio sound damp and lifeless. Thus, you also need to consider diffusion.
Sound Diffusion
Diffusion is like a bunch of smaller reflections. Scattering sound around a room with diffusers makes the sound fill a room more effectively, so you hear every sound of the spectrum clearly and fully without echo. Diffusers are usually placed on the wall opposite the sound source as well as the sides, so any place where a wall would reflect sound will instead diffuse it.
Diffusers are often made of wood or plastic, and have an uneven surface for the purpose of diffusing sound waves effectively. An added benefit of sound diffusers is that a lot of them also look really cool, so it’s like having wall art built into your acoustic setup. A good diffuser that fits in better in a space like a living room is a bookshelf, since books provide an uneven surface for sound to hit and diffuse from.
Figuring Out the State of Your Room’s Acoustics
Before you make changes to a room to improve the acoustics, you first have to identify any problems that currently exist. If you go out and buy a bunch of absorbers, and it makes no difference to the acoustics of the room, you’ve just wasted a bunch of time and energy before even diagnosing the problem.
The most obvious issue for diagnosing is echo. Does the room have a loud echo? Is it relatively empty? Are the walls bare? Does the room have a carpet or an area rug, or is the flooring hard and bare?
It’s also important to figure out where the sound is bouncing from. The positioning of speakers will impact where sound hits and reflects, and in what pattern it reflects.
If your speakers are facing diagonally relative to the shape of the room, the sound waves will hit the wall at that angle and reflect at the same angle.
If the speakers are facing straight toward the back of the room, the sound waves will bounce off the back wall and back toward the front wall where the speakers are, which is called an axial mode. This can often make mid-range and bass tones sound off, and create spots in the room where loudness varies.
How You Can Improve Your Room’s Acoustics
If your room has a lot of echo, you’ll benefit from mounting sound absorbers on your walls where the sound waves tend to reflect, relative to the positioning of your speakers. Mounting a diffuser on the back wall of the room will also help to ensure sound hitting the back of the room gets distributed and scattered better. It’s also a good idea to put bass traps in the corners of a room to make bass less boomy and overwhelming.
If you don’t want to go out and purchase sound absorbers or diffusers for aesthetic reasons or budgeting reasons, there are ways to position a room or add to it that improve acoustics in a more natural way.
Bookcases are great sound diffusers because of the uneven surface the books create. Canvas paintings can be fairly good sound absorbers, so you can utilize wall art by placing it strategically to absorb sound that would normally be reflected in that area.
Area rugs are incredible for reducing echo. Given the choice, opt for a medium or high pile rug, but a flat rug will still help. Mounting rugs on the wall also helps, as well as tapestries, which can both be aesthetically pleasing choices. Upholstered furniture also makes for good sound absorption.
Now you should have an understanding of how room acoustics work and how to improve the state of yours. Whether you’re setting up a recording studio for music or a podcast, setting up a home theater, or want to enjoy music on your speaker system to the fullest extent, knowing these basics should make your experience a lot better.
