Eliminate Echo and Reverberation with Gymnasium Acoustic Panels

Imagine the sounds of a high school basketball game: fans cheering, referees whistling, balls bouncing, shoes squeaking. All these noises become a big problem in a room where players can’t hear the referee’s calls and fans can’t fully follow the game because of all of the noise bouncing off the ceiling and walls.

Reverberation is a common and extremely detrimental issue in large rooms like school gymnasiums. You have probably experienced this uncomfortable basketball game soundscape yourself more than once. Understanding how to properly apply acoustic panels for schools with RT60 and speech intelligibility scores is the first step you can take to reducing echo in a large room.

Why Is Sound Quality so Poor in Gymnasiums?

The layout of a gymnasium sets it up for remarkably poor acoustics:

• Significant size: Large cubic volume with high ceilings
• Resonant surfaces: Hard, parallel, reflective surfaces like concrete block walls, hardwood floors, metal roof decking on every plane
• Open space: Wide open floor plan and minimal, if any, soft furnishings to absorb sound 

These factors combine to create an environment where sound bounces repeatedly from surface to surface before dying out, creating a cacophony of overlapping reverberating sounds.

Frequent changes to a multi-use room can make sound quality even worse. Lowering a dividing wall creates smaller rooms that intensify flutter echo. Retracting bleachers exposes more flat, hard surface area for sounds to bounce off of. 

Two Key Factors To Reducing Echo in a Large Room: RT60 and Speech Intelligibility

In order to find what noise control solutions, such as ceiling baffles or acoustic wall panels, will work best in your gymnasium or other large room, we’ll need to figure out two key metrics first. 

RT60

RT60 (reverberation time 60) measures the time it takes for sound to decay by 60 decibels after the source stops. Essentially, RT60 determines how many seconds a sound hangs in the air. A lower number means the sound in the room is more controlled and speech is easily heard. A high number means the room is more reverberant and sounds blend together. These are typical RT60 measurements in rooms where sound quality really matters:

• Recording studio: 0.2-0.5 seconds
• Classroom: 0.4-0.6 seconds
• Concert hall: 1.8-2.2 seconds
• Untreated gymnasium: 2.5-6.0+ seconds

When RT60 reaches over three seconds, sound quality becomes an issue in most rooms. New sounds arrive before old ones fade and create a confusing sonic landscape. For gymnasiums and large multi-purpose rooms, our recommended target RT60 range is 1.0-1.8 seconds.

To measure RT60, an acoustic engineer produces a loud sound in the room, usually by firing a starter’s pistol or popping a balloon, and records how long the sound reverberates using a microphone or sound level meter. These measurements are taken at multiple points throughout the room to account for any variation. After the sounds are recorded, the acoustic engineer either feeds the recordings into software that produces the RT60 number or calculates the number using the Sabine equation.

Speech Intelligibility

Speech intelligibility goes beyond RT60 to quantify how much speech can be understood in a room. There are two core speech intelligibility metrics:

• STI (Speech Transmission Index): Measures the intelligibility and quality of speech transmission in a given space on a 0-1 scale; gyms often score 0.30–0.5; the target for a gymnasium is 0.60+.
• %ALCons (Articulation Loss of Consonants): Measures the percentage of speech sounds lost in a given environment, specifically targeting consonants; a high loss of consonant comprehension gives the sound of garbled speech. The %ALCons target for a gymnasium is 10%.

Optimal speech intelligibility isn’t just nice to have, but essential. Consider all of the important messages that need to be clearly relayed in your gymnasium. PA announcements during emergencies. Coaches’ instructions during practice and games. Special events: assemblies, graduation ceremonies, guest speakers, pep rallies. ADA compliance considerations for hearing-impaired students and faculty. Sound clarity is imperative, and solutions are available to help you get there.

How To Reduce Echo in a Gymnasium

Before you take steps to reduce echo, it’s helpful to know the science behind sound reverberation:

• NRC ratings (absorption coefficients): Measures the percentage of sound that is absorbed by a surface; higher numbers that are closer to 1.0 are more absorbent.
• Surface area: Determines the amount of surface space that sound has to bounce off of.
• Sabins: Combines the NRC rating with surface area in a single unit of sound absorption; 1 sabin equals 1 square foot of a perfectly sound absorbing surface.

What these measurements tell you is that generally, a high volume of open space is more susceptible to reverberation, and large rooms need to integrate sound absorption. 

In a gymnasium, sound absorption panels are most effective when placed at an upper wall surface, ceiling and roof deck, and at end walls behind goals or stages. Too often, we see multi-purpose rooms that have only one treated wall or have too few panels installed, leading to minimal improvement. For significant RT60 reduction and optimal speech intelligibility, our rule of thumb requires treating 15–25% of total surface area. That’s more space than you might think in large rooms like gymnasiums. To ensure you receive a maximally effective noise control treatment, contact the experts at O’Neill.

Answering Questions about Sound Panels for Gymnasiums

O’Neill Engineered Systems: The Authority on Sound Panels for Gymnasiums

Proper sound paneling is crucial for school gymnasiums. Knowing how to measure and achieve an ideal sound clarity will set you up for success. As a leading provider of sound paneling for school gyms, the acoustic experts at O’Neill Engineered Systems can design and install a custom noise control solution for your school gymnasium. Be sure to check out our Complete Guide to Noise Control with Sound Absorbing Panels to learn even more.