Noisy reverberant spaces make understanding speech difficult and create an uncomfortable environment.
What is a reverberant space?
When most people refer to a noisy reverberant space, they usually will describe it as a room with a lot of echo. While that's not quite correct technically, we've all experienced the effects of being in a large empty room in a new house, and the difference in acoustics when we add things like carpeting, furniture, and drapes.
So What's Going On?
When a space has a lot of hard parallel surfaces like drywall and ceramic tile, those surfaces are said to be reflective. If you clap your hands, the sound waves will bounce back and forth until it runs out of energy. The longer the distance between two parallel surfaces, the longer the reverberation time.
What are the negative effects of a reverberant space?
Reverberant spaces are the enemy of speech intelligibility. When someone speaks, their voice is reflected off of the walls and back to the receiver. As a result, they hear another instance of the speech that is lagging slightly; the larger the room, the longer the delay. This disrupts the brain's ability to interpret what is being said. People will usually respond by speaking more loudly, which makes the problem worse.
Some typical spaces where reverberation and speech intelligibility an be a problem:
- Conference Rooms
- Houses of Worship
- Bars & Restaurants
What's The Solution?
Treating noisy, reverberant spaces is a pretty straightforward fix based on the acoustic principals of absorption and diffusion. The solution is to add enough absorptive and/or diffusive material to the space to stop sound waves from bouncing around off of the hard reflective surfaces. Lightweight, porous materials such as fiberglass and melamine foam make excellent sound absorbers. Acoustical diffusors are typically fabricated from dense molded fiberglass or wood, and are available in many shapes and configurations based on the application. They reduce reverberation by breaking down the sound waves and scattering them in different directions. Diffusion is desirable in spaces where reverberation needs to be reduced, but still sound "live", such as performance theaters.