How’s that sound?

Previously, I wrote about how terroir affects our learning and what we can do to improve the physical design of our learning spaces. In those posts I considered our visual and tactile experience of learning spaces. What about acoustic design?

Learning is challenging enough when you can hear what’s being said. But when the course material you’re trying to understand sounds like a mumbled recording of a garbled drive-through speaker played over an airport public address system, the experience is simply painful.

The Problem

We often personalize sub-optimal situations in learning. Instead of properly locating the issue, we blame each other.

Like drivers who get mad at each other because they fail to recognize the design flaws of on-ramps or merging lanes, teachers and students get frustrated with each other without accounting for the poor design of their acoustic environment.

Poor acoustics make things hard on transmitters and receivers alike. We use a lot of energy to correct for errors and separate the signal from the noise. Negative effects of bad acoustics include:

  • Worn out voices
  • Fatigue
  • Ringing in the ears
  • Elevated blood pressure and cortisol levels
  • Frustration and resentment

While it is true that some teachers and students could enunciate more clearly and use their voices more effectively, it is also true that most of us don’t understand acoustics well enough to know what’s happening in our environment or what could make it better.

We need to distinguish the acoustic environment from the people in it. Some teachers I know have purchased microphones to amplify their voices. Unless they address the surrounding issues, they will continue yelling on the freeway and contributing to the overall noise problem in a louder way.

Meanwhile, if someone is trying to share information and you can’t understand what they’re saying, you’ve both lost time, money, and opportunity.

The good news is that we can improve our acoustic environments. Here are a few observations and tips.

Your classroom or home office sounds (unintelligible…)

Have you ever been in a lecture or concert hall where the sound is clear without being loud, and the tone is warm and intimate no matter how far away you are from the stage?

Those rooms are created with tremendous care. Take for example Benaroya Hall, home to the Seattle Symphony. Benaroya Hall was completed in 1998 at a cost of $120 million. Gordon Hempton, author of One Square Inch of Silence, interviewed lead architect Mark Reddington, who worked on the project for 12 years. Here is what Reddington said:

“Reverberation is important for the way the symphonic hall works, and then there are characteristics of the room that diffuse the sound, which is also essential for symphonic hall acoustic quality. There are a number of characteristics of the room: the overall room geometry, the geometries of all the surfaces, the configuration of the balcony. (p.78)

That is not what your room sounds like. However, you can use some of the same basic principles to greatly improve the acoustics in your space at school and home.

A well-designed acoustic environment:

  • filters out external noise
  • has an RT 60 (reverberation time) of less than a second
  • allows for more direct signal (i.e., when the speaker is speaking, you can hear her voice without strain, as opposed to having to constantly separate original signal from echo/reverb as in a crowded gym)

Anything you do will be an improvement. When was the last time you did anything to lower the RT 60 in your learning space or just thought about what might create a cozy, intimate signal?

Acoustics are customizable

You can create different acoustic signatures depending on your purpose.

Scientific research makes it easier to understand and design acoustics on a budget.

In brief: Sound is compression of molecules in the air – if you want to slow/stop them, you need mass.

With all due respect to my cousin’s 1970s garage band, stapling eggshell cartons to walls isn’t enough.

Sound is energy – movement converted to heat which then dissipates – and, to repeat, absorbing that energy requires mass.

Unless you’re a bat get rid of the echo

For starters, mount some 1×2 slats on a wall with moving blankets underneath them. This creates a diffuser/absorber that attenuates energy in the mid-range (where the human voice is).

You can treat a ceiling and one wall in this way for about $20-50/square meter.

Make sure that parallel surfaces aren’t both bare – you want to minimize reflective echoes and reverberations.

If you want a better sounding room, install:

  1. a couch
  2. a tapestry
  3. acoustic panels (rock wool and cheap frames)

Now that you’ve added some mass that warms up the room and focuses on the human voice, it’s time to get rid of some noise clutter.

The power you save should be your own

I was sitting in the Hollywood Hawaiian Hotel
I was listening to the air conditioner hum
It went mmmmmm… -Warren Zevon

Lighting and consumer electronics bring a lot of noise into our lives. Air conditioners and refrigerators are obvious culprits, but there are more subtle, buzzy, high-pitched whiners that screw with us all the time.

You may not consciously notice a low-level odd order harmonic distortion unless you put your ear next to a wall power supply or meditate on a flickering fluorescent light tube, but that energy is constantly floating around you. Parts of your brain work hard to reconcile it but you can’t do anything with it, so you spend more energy trying harder to alternately resolve and ignore it.

Listening to information in that kind of environment is like looking through a dirty window. Cleaning it reveals a beautiful view and creates a calming effect. Listeners’ shoulders literally drop when they can hear messages they need without having to work so hard.


Most classrooms and home offices do not adequately filter out external noise, minimize odd order harmonic distortion, or adequately absorb echoes and reverberations.

The poor design of these learning environments create negative effects on people that impede learning.

We all need to learn more about our acoustic environments so that we can modify them in ways that support calm, focused, attentive listening.

Please Contact Me to learn more and continue the conversation.