The MARRS Project: How Classroom Audio Amplification Levels the Playing Field for Students

When we think about helping students succeed, we often focus on curriculum, teaching strategies, and technology. But what about something as basic as making sure every student can hear the teacher clearly? That’s exactly what the MARRS Project set out to investigate — and its findings transformed how educators think about classroom acoustics.

The Mainstream Amplification Resource Room Study (MARRS Project) began in the late 1970s under the leadership of Dr. Carl Crandell and Dr. Fred Bess. Its goal was simple but powerful: determine whether using sound-field amplification systems — which broadcast the teacher’s voice evenly throughout the room — could boost learning for students, especially those with mild or undiagnosed hearing loss. The results were clear and have shaped best practices for decades.

Key Findings from the MARRS Project

1. Academic Gains for All Students
Students in amplified classrooms showed significant improvements in reading, language development, and overall academic achievement compared to students in traditional, unamplified classrooms. While the biggest gains were seen in students with mild hearing loss, all students benefited from clearer, more intelligible instruction.

2. Better Listening and Attention
Teachers reported that students stayed engaged longer and followed directions more easily. With better speech clarity, students needed fewer repetitions and spent less time struggling to catch what was said.

3. Fewer Special Services Needed
One of the project’s most remarkable findings was that many students who would typically be pulled out for extra help — due to mild hearing loss or minimal learning difficulties — were able to thrive in the general education classroom when sound-field amplification was used. This meant more inclusive classrooms and better use of special education resources.

4. Less Vocal Strain for Teachers
Teachers also reaped the benefits. Amplification allowed them to speak at a comfortable level without straining their voices to reach the back of the room. Many reported less vocal fatigue and improved classroom management because students could hear instructions the first time.

5. A Cost-Effective Solution
Compared to the expense of extra resource services or specialized one-on-one instruction, sound-field amplification is relatively affordable and simple to implement. It’s a straightforward way to remove barriers to learning for a wide range of students.

Why the MARRS Project Still Matters

Today, the MARRS Project is widely cited by organizations like the Acoustical Society of America as clear evidence that improving classroom acoustics pays off for everyone — students, teachers, and schools alike. In an era where inclusion and equity are at the forefront of education, ensuring every child can hear the teacher clearly is a small but powerful step that levels the playing field.

Good classroom acoustics shouldn’t be an afterthought. As the MARRS Project proved decades ago, amplifying the teacher’s voice doesn’t just make things louder — it makes learning accessible to every seat in the room.