Signal to Noise Ratio

In 2015, as the new head of instructional technology for a school district of 19,000 students, 1,300 teachers and classrooms, and 2,500 staff, part of my role was to plan, implement, and support the audio-visual equipment over our approximately three dozen campuses and ancillary sites. We were transitioning from projectors and interactive whiteboards, to interactive flat panels. Think of the new solution as a flat-panel TV, but with touchscreen, embedded instructional software, and rugged to withstand a classroom environment. We were transitioning from DVDs to digital video. But one thing that was a constant was the audio enhancement systems we had been installing for seven or eight years already.

Purchasing big-ticket items in a school district comes with a lot of responsibility, a lot of time speaking at board meetings, and a lot of planning and budgeting. Another thing that the role has in great abundance is the opinions of others on how to best do your work and accomplish district goals.

Our audio enhancement systems, at the time, are something that we did universally in all of our classrooms. It was one of our district standards. While many folks loved the systems, used them every day, relied on them, and praised our standardization, others felt that they were a waste of district resources and many people were not taking advantage of them. I constantly heard the, “my voice is loud enough, so I don’t need to use it,” argument.

I’ve never been someone to just take what I’m handed and continue to “do what we’ve always done”, so I decided to dive into the research because I couldn’t imagine that we invested in this significant instructional infrastructure just to ease the voices of our teachers. Each system cost roughly $1,000 including installation. At 1,300 classrooms, that is an initial $1.3M investment with ongoing support costs and a refresh/replacement cycle for the equipment. These systems are not some casual add-on to a classroom- they require installation, ceiling mounted speakers, a tie-in to the computer system, microphones, etc.

What I learned about the importance of these systems in the classroom is something that served me well in my role and in sustaining this important equipment for our students (because it is for them and not the teachers), but also in my life.

Enter the concept of the “signal-to-noise ratio”. If you already know what it is, please don’t blurt it out and spoil it for the kids who didn’t read that issue of Modern Acoustics or get their degree in audiology.


At it’s most basic, signal-to-noise ratio is the proportion of how much sound you want to focus on (signal) is present compared to the background noise. Now, let’s step into the classroom.

Aimee sits in the front row. She has students to her sides and behind her, but no one in between her and the front of the room. Assuming that the teacher spends most of their time in the front of the room, she is much closer to the signal (teacher’s voice) than many other students in the room. Because of the lack of other students in the vicinity and he proximity to the teacher, the signal-to-noise ratio plays in her favor.

Tyrie sits in the dead center of the classroom. He has students in front, on the sides, and behind him. He also sits under the ceiling mounted projector which has a fan running throughout class. With the students and projector creating an increase in background noise, and his distance from the teacher decreasing the level of signal, the signal-to-noise ratio starts to impact his learning.

Finally, we have Lia, who is sitting in the back row and has students to the sides and in front of her, with every conversation impacting her in some way. Every sneeze and every sniffle lie between her and the teacher. In addition to the student noise, the projector fan, the speaker for announcements, every shift in a chair, and every dropped item in the classroom increases the background noise, for a signal (that regardless of teacher volume) is still lower for her than for her counterparts.

If you include the fact that our students are interacting with more and more multimedia in class as well and most of that signal comes from the front of the room if you don’t have a dedicated system, you start to understand what a pivotal role signal-to-noise ratio can play in the classroom and in our lives.

Once we had a conversation about the research and signal-to-noise ratio with the board and district executive leadership, the hesitation to continue the project ceased. We then turned our efforts to making sure that our teachers understood that regardless of their vocal volume, their students’ learning experiences were vastly different depending on where they sat.

Now let’s take this a step farther and layer on top of this the fact that the idea of signal-to-noise ratio doesn’t only apply to sound. If I’m in the front of the room, I also see everything that the teacher intends for me to see, and nothing that my classmates are doing behind me. If I’m sitting in the back of the room, I see every student, every movement, every door opening; every possible distraction is between me and the intended experience.


Think of your own work now. Think of how many tabs you have open on your computer while you are working on a presentation or researching for a project or preparing for the big meeting. Think of how many notifications you get on your phone, your tablet, your computer, and even your watch. Think of how many disruptions exist from folks walking in or through your work area. Think of how often you are reading emails or checking on social media accounts when you’ve got a looming deadline.

This is all a signal-to-noise problem. In the classroom, we can design and implement a system that serves to push the signal-to-noise ratio back in favor of the learner, but this can be much more difficult in our daily lives. I’ve taken two tips from one of my favorite TED Talks (5 ways to listen better by Julian Treasure) and adapted them to help me right my ship when I feel I’m moving too far into the background noise of my work.


Treasure mentions that three minutes of silence a day helps to recalibrate your hearing so that you can better hear quiet noises again. I echo this, but add that you should try to pull away from the work, from the screens, from everything for a few minutes a day, not only to recalibrate our listening, but to recalibrate our sight and one of our most important and very limited resources, our attention.


When you are in a noisy environment (noisy with sound or with distractions), take a few moments to try to identify each individual sound, each person’s voice, each item that is pulling our attention away from the work that we should be focusing on.

Identify them, so that you can address them. I once took this inventory of the number of notification and status lights that exist in my room at night compared to what would have been in my parent’s room 25 years ago. Since I spent the time to identify, it became easier to address them and limit the distractions, to improve my signal-to-noise ratio.

Once you become more aware of the items that are pulling you away from your work, that are impacting your signal-to-noise ratio, you can set yourself on a path to sharpened focus, increased productivity, heightened listening, and improved learning.