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Room Acoustics 101

Whether you’re setting up an elaborate stereo system or simply trying to hold a conversation, some rooms seem to have a better sound than others. Many large rooms sound hollow and echo-filled, while others are so absorbent that it sounds like your voice hits the floor the moment it leaves your mouth.

When either of these effects happens, it’s rarely due to the sound source. More often than not, it’s caused by the environment — specifically, the structure of the room and the materials in it. This discussion centers around acoustics, the primary driver of how pleasant or unpleasant a space sounds.

What Are Room Acoustics?

Understanding room acoustics starts with knowing what acoustics entails. Acoustics are the way sound waves interact with the space around them. When something emits a sound, whether it be your voice or a stereo speaker, it projects sound waves outward. The waves make contact with a variety of different surfaces, from walls to ceilings to tables.

How the waves interact with those surfaces depends on the nature of the surface. Sometimes the sound waves will bounce off, while other times they’ll be absorbed. As this effect adds up across different surfaces throughout the room, it generates a specific acoustical sound for the space — which could have anything from huge amounts of reverberation to none at all.

Why Are Room Acoustics Important?

It may not seem like a big deal if a room echoes a bit or if the sound falls flat. Bad acoustics may be bearable, but good acoustics can bring some worthwhile benefits to everything you do in a room. Here are a few of those benefits:

1. Improved Concentration

One way bad acoustics can manifest is by magnifying small sounds. Something as simple as the click of a dropped pen or the squeak of a chair can echo around the room with every movement reaching your ear.

This type of environment is far from ideal when it comes to concentrating. If people are trying to study or work on something, they probably won’t have much luck amid that many distractions. Ambient noise is particularly detrimental to young students.

Improving the acoustics of a room can make a world of difference when it comes to concentration. With so many small sounds absorbed and outside sounds kept out, people can better focus on whatever they’re there to do.

2. Increased Productivity

Once you’ve adjusted the acoustics of your room to allow for greater concentration, it follows that you’ll be able to work more productively. Without the distractions of all the small movements within a 20-foot radius, people can stay on task and get more done in a given amount of time. This fact makes it especially important for classrooms and offices to have good acoustics.

3. Better Overall Sound Quality

Sometimes, you’re focused on the sound itself in addition to its effects. If you’re trying to figure out the acoustics of an auditorium or sanctuary, it’s vital the structure and arrangement of the room are conducive to good sound quality. With good acoustics, everything can sound its best, letting your sound accurately represent the work that was put in.

What Affects Room Acoustics?

Since acoustics are driven by interactions between sound waves and different surfaces, it makes sense that many different factors are at play in a specific room’s acoustics. Three things in particular affect the overall movement of the sound waves in a room — hard surfaces, noise sources and high ceilings.

1. Hard Surfaces

Much of what drives how a sound wave interacts with a surface is whether the surface is hard or soft. A flat wooden board will have a much different effect than a cloth curtain.

That’s why it’s essential to consider the arrangement of hard surfaces in your room. While soft surfaces tend to absorb sound waves, hard ones reflect them, causing reverberation. The more hard surfaces there are in a room, the more reverberation there will be. With too much, it can become hard to understand the sounds you’re hearing.

2. Noise Sources

Sometimes the surfaces aren’t the only thing that could be causing problems — the sound waves themselves are just as significant. If too many sounds are produced in a given space, they can overlap so much that it becomes nearly impossible to make out any of them individually.

If you’ve ever been to a party in someone’s home, you may have experienced the effect of multiple voices mixing together at once, preventing you from understanding anyone. Limiting the number of sound sources can do a lot to improve intelligibility.

3. High Ceilings

Even if your sound source is facing a horizontal direction, sound waves will still go upward and come into contact with your ceiling. How that happens depends on the ceiling’s height. The farther the sound waves have to travel, the more reverberation there will be. If you don’t want reverberation in your room, you’ll want to make sure you have a low ceiling. If the ceiling is high, you may want to cover it with sound absorbers.

What Are the Elements of a Room With Good Acoustics?

To some extent, you can tell if a room has good acoustics simply by walking in and creating sound. But that won’t tell you everything, especially if you don’t know what to look for. Here are some of the main qualities of good room acoustics design:

1. Minimal Reverberation Time

Reverberation time, or RT60, refers to the time it takes for a sound to fade away in a room — or more accurately, to decrease by 60 decibels. Reverberation is caused by sound waves bouncing off various surfaces, and the more reverberation occurs, the longer the sound will remain audible. Lower reverberation times indicate the sound is being absorbed by something without much reflection occurring.

When you optimize a room acoustically, consider reverberation time. For the best results, you’ll want to take precise decibel measurements, but you can gauge by ear if the reverberation is exceptionally high or low. The ideal room will have the same reverberation time across all frequencies.

Good reverberation time depends on the size and purpose of the room. Auditoriums typically favor reverberation times of 1.5 seconds-2.5 seconds, while smaller rooms such as classrooms and bedrooms sound best if reverberation times are kept at less than a second.

2. Uniform Sound Distribution

When you’re judging a room’s acoustics, make sure you don’t do it all from one spot. A room may have excellent acoustics in one spot and worse acoustics in another. It all depends on how the sound is distributed.

Sound distribution is particularly important for large rooms, like auditoriums. In those settings, you want to make sure the sound from a speaker, musical group or any other source reaches everyone in the room. If an orchestra performs a concert, the people in the front row might be able to hear it fine, but you need to make sure the same is true for the people in the back.

Smaller rooms don’t usually have as much of a problem in this area, but you can still consider and fine-tune the sound distribution.

3. Appropriate Sound Levels

Improper sound distribution is frequently the problem when people are not able to hear sounds in a room. Other times, the problem is that the sound source isn’t loud enough. This factor has less to do with the room and more to do with the people or sound system it’s intended to host. You need to be sure your sound levels are high enough for you to hear them over any other noises. Only then can you try to fix the acoustical qualities of the room itself.

4. Low Background Noise

The focus of acoustics is usually on the sounds you want to hear, but you can’t ignore the fact that there will be unwanted sounds as well. Whether it’s cars driving past outside or the air conditioning unit across the room, background noise is inevitable. That’s not to say you can’t limit it. For the best acoustics, try to find a room that isn’t near any intrusive external sounds. If your room is right by a road or has an air conditioning unit directly outside the window, it’s probably not the best choice for acoustical balance.

5. Minimal Echoes

In many cases, you probably don’t want your room to have much echo, if any. Most echoes occur due to concentrated reverberation, where a single surface reflects the sound waves toward you. Flutter echoes are slightly different, as they involve sound waves bouncing back and forth between two parallel surfaces.

In both cases, the echo can quickly become a problem. When you hear the same thing more than once in rapid succession, especially if it overlaps, it can lower intelligibility. It’s advantageous to find a room that doesn’t cause echoes or work to reduce existing echoes in your current room. In smaller rooms, echoes are less of an issue, but for auditoriums and other large spaces, be on the lookout.

How Can I Fix Room Acoustics?

The above criteria are great things to consider when looking for a room with good acoustics. But what if you’re already stuck with a room that’s lacking in those areas? Thankfully, you still have options for improving your room’s sound. Through techniques like diffusion, absorption, tuning and soundproofing you can help counteract acoustical issues.

1. Diffusion

If the problem with your room is mainly bad sound distribution, diffusion may be the best solution. Diffusion refers to the process of spreading sound waves out evenly across a space. This process is necessary because sound waves often get concentrated in one area of the room at the expense of other areas.

You can accomplish diffusion by using specialized objects or wall panels to deflect sound outward. These objects often have a convex shape to distribute the sound waves widely, though new designs are continuously being developed. Diffusion isn’t used when you want to remove sound waves from a room — only when you want to reposition them.

2. Absorption

In contrast to diffusion, absorption is the best solution for removing sound waves from an environment. If your room has too much reverberation or echo, absorbers can help by lowering the number of sound waves moving through the room and counteracting some of the surfaces they contact.

Absorbers often come in the form of wall or ceiling panels. Since they’re made of soft material, they absorb the sound waves that hit them instead of reflecting them. In doing so they essentially take those sound waves out of the picture.

3. Tuning

Diffusion and absorption technically qualify as tuning in the broadest sense, but there is a more specific meaning of the term tuning. Digital tuning refers to the process of altering a room’s acoustics by projecting sound waves into the air in a certain way. Whereas diffusion redistributes existing sound waves and absorption removes them, tuning adds new sound waves.

You can accomplish digital tuning with the help of a digital equalizer, or digital EQ. Digital EQs appear in many sound systems to improve the quality of the projected audio, which makes them ideal for rooms intended for sound system use. As a digital EQ projects audio, it adjusts the volume of different frequencies for optimal acoustics. If you have a problem getting sound waves from your audio system to reach a particular area of the room, digital EQs can help balance the sound across the space.

4. Soundproofing

Sometimes the issue with your room’s sound stems from outside sources. You can put up as many absorber panels as you want, but it may not stop those outside sounds from getting in. The alternative option is to soundproof. Unlike the other options, soundproofing doesn’t involve manipulating sound waves within the room — it keeps them from getting in to start with. Most soundproofing is done by putting absorbent layers inside the walls, separating the indoor and outdoor sides so sound can’t get through.

Where Can I Get Help With My Room Acoustics?

No matter what your room is used for, good acoustics are incredibly valuable. In a classroom, they can help students focus. In an auditorium, they can help back row audience members hear the performance. In a lecture hall, they can help guests project their voice. Where factors like reverberation time and sound distribution are lacking, you can install acoustical panels to boost the sound quality.

Where should you get these panels, and how do you decide where to put them? Look no further than Illuminated Integration for the answer. We offer several acoustic improvement options, and we’ll be happy to help you integrate them in a way that gives you the best possible sound experience. Get in touch with us today to get started or to ask any questions you may have!