The Science Behind Classroom Audio

It’s pretty safe to say that, if students can’t hear the lesson, they can’t
understand what’s being taught. Whether the teacher or another student is speaking,
hearing and understanding the speaker is critical to student learning. Don’t
just take our word for it—research confirms it.

In 1977, the U.S. Department of Education began funding the Mainstream
Amplification Resource Room Study (MAARS Project), a three-year study to test
the effects of using a wireless microphone to amplify the teacher’s voice to
help children with minimal hearing loss stay in mainstream classrooms. Over the
course of the project, researchers discovered that the amplification system didn’t
just increase achievement for students with hearing loss—ALL students had
significant gains in their learning and success.

Looking more closely at this discovery, we can attribute this to two things:
signal-to-noise ratio and the inverse square law. The signal-to-noise ratio for
a classroom is how loud audio from the teacher or multimedia is compared to other
noise in the classroom. Research shows that for students to understand, they
need the teacher’s voice to be at least 15 decibels (dB) louder than any
background noise. Since the average conversational voice is about 65 dB and
average classroom background noise is 50 dB, it seems like there shouldn’t be a
problem. That’s where the inverse square law comes into play and complicates

The inverse square law demonstrates that every time we double the distance from a
sound source, that sound’s intensity diminishes by 6 decibels. Students who are
further away from the teacher receive the sound at a much lower level, making
it difficult to understand what is being said. This can result in more
distracted students, increased behavior issues, and lower academic achievement.
All this can happen because sound from the teacher isn’t reaching every student
at a level they can hear and understand.

Some may argue, “That’s why teachers have a ‘teacher voice.’” The problem is that
just using a louder voice can come across as yelling to some students,
especially those sitting in the front row who already hear just fine. Those
louder voices can also have a harsher tone, signaling to some students that the
teacher is upset. Speaking loudly is a greater drain on a teacher’s energy and
stamina, and it can strain their voices. For the sake of student experience and
teacher health, a natural, soothing tone is best in the classroom.

One solution to all of these issues is installing an audio system in every classroom. With distributed audio systems, the teacher wears a wireless microphone around their neck. This allows them to speak in their natural voice, from anywhere in the room, saving their energy and reducing strain on their vocal cords and throat. Audio from the microphone is transmitted through a receiver, to an amplifier, and is sent to speakers placed in the ceiling throughout the room. This gives all students the opportunity to hear, no matter where they’re sitting in the classroom.

The MARRS Project may have happened four decades ago, but those discoveries are
still valid today. If student learning and achievement is our focus, we need to
ensure all students can hear. Classroom audio systems are a clear winner when
it comes to ensuring every student has the chance to hear and learn.