How Room Acoustics Work

Old Performance Hall

Room acoustics play an important part in the overall comfort and usefulness of any room or space. Often times the acoustics of a room can make it uncomfortable for the person occupying it. However, many people fail to understand the basics of what makes the sound in a room natural and pleasing to the ear. Bad acoustics in a room are not inescapable, with the proper knowledge and materials, any room can be acoustically pleasing.

Direct Sound vs Reflective Sound

Millenium Park Theatre

Sound travels in waves at the very fast speed of over 1100 feet per second. When we hear sound we are hearing both direct and reflective sound. Direct sound is the sound we hear first because it is made up of the sound waves that travel the shortest distance directly to us. Reflective sound is the sound we here later, in an echo, because it is the sound waves bouncing off objects, often multiple times, and being sent back to us. Because the reflective sound travels further we hear it in reverberations as an echo. However, because sound travels does travel so fast the waves overlap and become distorted rather than distinct echoes.

Acoustic Materials to change Reflective Sound Distortion

When considering the acoustics in a room the most important thing to remember is that the more hard flat walls, ceilings and floor space you have the more surfaces there are for sounds to be reflected off. Also consider the amount of angles these flat surfaces create. Between just two flat surfaces a sound wave can be bounced at least 60 times a second.

Minnesota Orchestra HallWhen you factor in the amount of space and angles found in a normal room with six flat surfaces (four walls, ceiling, and floor) the number of times that a sound wave can be reflected enters into the thousands, all at full strength if left unhindered. Altering these surfaces with proper acoustics material will provide drastic changes to reflective sound and the acoustics of the room.

Absorbers and Diffusers

Acoustic absorbers are products made from special materials, often made of foam or cloth, that absorb the energy of the sound waves reducing the amount of sound that is reflected. Diffusers are shaped materials that alter a flat surface in order to scatter the sound waves around the room, much like a wave of light through a prism. Most modern acoustics material combines both principles of absorption and diffusion in to a single piece. The combination of both reduces both the amount and intensity of reflective sound that reaches the ear and reduces the distortion reflective sound causes.

Acoustical Barriers

Often called noise or sound barriers, acoustical barriers help to not only block sound from leaving the room, they also help block outside sounds from interfering with the sound in the room. Although absorbers and diffusers dampen the sounds that leave and enter the room, sound barriers are denser materials. This denseness leaves little room for sound to enter or escape reducing the sound distractions created outside and the sound distraction for neighboring rooms.

Making Walls Quiet Whitepaper CTA

Photo credit: allison.hare / Foter / Creative Commons Attribution 2.0 Generic (CC BY 2.0), passer-by / Foter / Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0)

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