Improving the Air Force Band Room

All rooms need to have a good balance of acoustic energy with surfaces which provide specular reflection, diffuse reflection and absorption. For example a good meeting room may require the room to have more absorption and diffuse reflection and less specular reflection. This may provide a room with low reverberation allowing for a speaker and or conversations to be heard clearly.

On the other hand a concert hall for live music may have more specular reflection and diffuse reflection than absorption. This may provide a room with higher reverberation which would enhance the sound of the live performance. Of course the overall purpose of the room, its size, shape and the size of the performing group must also be considered.

A band practice room also requires a balance of reflected, absorbed and diffused sound energy to allow the musicians and conductor to adequately hear each other and be able to interact. A good practice room may require something in between a meeting room and a live concert hall while maintaining emphasis on specular reflection and diffuse reflection. The balance of all three parameters would depend on the size of the band and size of the room.

An important element for a practice room is for it not to cause musician fatigue. Musicians playing non- amplified acoustic instruments should not have to work too hard to get the sound energy from the instrument into the room. A room with too much absorption will remove sound energy and may force the musician to work hard thus resulting in “practice” fatigue. To avoid this, the practice room should have a good amount of surfaces that provide specular reflections and diffuse reflections to keep the sound energy in the room.

In addition, a number of factors need to be considered in order to have a good practice space including the size of the band, the volume of the room, the ceiling height, the ratio of width, length and height, the RT60 time in seconds of the room and room modes to name a few. Although it may be hard to achieve, a good practice room should allow for the band members and band leader to be able to hear each other in a way that might closely resemble live performing venues they may perform in. Many of these performing venues tend to be somewhat reverberant.

Sondare Acoustics recently performed an acoustic analysis of The U.S. Air Force Band of Mid-America practice room. The room is used for many different size bands. It has many diffuser and absorption panels on the walls and ceiling, along with absorbing carpet on the floor. The result is a somewhat low reverberation time that might not be ideal for a band practice facility.

After extensive onsite testing and quantitative acoustic analysis, initial recommendations were made to decrease the amount of absorptive surfaces and increase the RT60 or reverberation time of the room (The RT60 time is the amount of time in seconds it takes a continuous sound in a space to decay 60dB after being turned off). The decrease in absorptive material should make it easier to maintain a good level of acoustic energy in the room thus reducing musician fatigue and providing improved instrument clarity.

Given the geometry of the room, additional recommendations were made to provide for adequate direct/reflected sound ratios from the walls and ceiling.

The band intends to work through the recommended changes to improve the room and possibly make additional improvements as time and budget permits. Sondare Acoustics thoroughly enjoyed working with members of the band to understand desired improvements and potential solutions and looks forward to assisting with achieving an improved practice facility.

Disclaimer of Endorsement:

Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government, and shall not be used for advertising or product endorsement purposes.