How to Acoustically Treat a Classroom

1. Ensure that the NC (Noise Criteria) in the Room is Not Too Loud

Noisy air conditioning, mechanical equipment, or other background noise can contribute to a rattling that makes it difficult for students to hear. This is especially true for space heaters or window AC units that are much noisier than their central AC counterparts. Because of this, students directly seated next to the units will find it the instructor’s words garbled by the nearby source.

Where possible, move this equipment as far away from students as possible. Also, ensure that speech is amplified so that even students in the rear next to the noisy equipment will be able to hear.

Ask a soundproofing or acoustical consultant to come and measure the Noise Criteria of the space to ensure it is below acceptable thresholds. NC levels in classrooms should often be below NC-30 to NC-35. The equivalent classroom dBA level is 38-42 dBA.

2. Use Acoustic Treatments to Minimize Reverberation

Acoustical Panels or high-NRC Acoustic Ceiling Tiles are needed to ensure that reverberation time does not exceed 0.6 seconds, per ANSI S12 – Classroom Acoustics. If the reverberation time exceeds this limit, then you will likely lose some speech intelligibility, making it difficult for students to hear. Conversely, you can also ensure that at least 70% of the ceiling area is covered by high-NRC acoustic tiles to meet most classroom acoustical guidelines.

Acoustic panels are especially necessary in auditorium style classrooms, as amplified speech is often used in them. Amplified speech reverberates more than unamplified speech, and because auditorium style lecture halls are so large, the echo that is created is even worse than it would be in a normal classroom. Without the proper acoustic treatment, students in the lecture hall likely won’t be able to understand the lesson, and neither would any students watching the lecture online.

3. Isolate Classrooms from Noisy Areas

Classrooms should be separated from noisy spaces by STC-rated walls. This may be achieved with the use of Mass Loaded Vinyl or other soundproofing materials in the wall between classes and loud areas, such as corridors, bathrooms, and mechanical closets. While the STC between adjacent classrooms should be 40-45, the STC of walls between classrooms and mechanical rooms should be at least STC 60 to meet ANSI and LEED requirements.

Many schools hire acoustic consultants to help ensure that STC walls are designed properly to meet the required STC rating. Students shouldn’t have to hear what others might be talking about in the corridor while trying to take a test. Also, they shouldn’t be able to hear what might be going on in an adjacent restroom if one happens to be right next to them. It’s important that students have an acoustically comfortable and soundproof classroom, not just because it’s required, but also so they have an environment conducive to learning.

How to Acoustically Treat a Classroom

By properly soundproofing the classroom, providing adequate acoustic treatment, and ensuring that background noise is at acceptable levels, you can ensure an acoustically-refined classroom environment for students to focus and learn.