Acoustics in the Workplace, Part 2

By Bonnie O'Leary

October 2009

Editor: This may be a topic that you haven't thought much about. I mean, is there anything you can really do about it anyway? The answer is yes, and here's some information on what you can do to improve acoustics in the workplace.

This is part two of two parts.

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Here's Part One

Classroom Standard - ANSI S12.60

The ANSI S12.60-2002 Acoustical Performance Criteria, Design Requirements and Guidelines for Schools standard was created by ANSI along with the efforts of the US Access Board and the Acoustical Society of America. This standard tries to create a classroom environment that optimizes speech understanding. Unoccupied classroom levels must not exceed 35 dBA background noise level; unoccupied classroom reverberation must not surpass 0.6 seconds in smaller classrooms or 0.7 seconds in larger rooms. The sign-to-noise ratio, or the difference between the teacher's voice and the background noise, should be at least +/- 15dB at the child's ears.

The ADA requires that "communications with persons with disabilities be as effective as communication with others....", but standards acceptable to normal hearing adults are not acceptable for HOH adults. The integration of Classroom Standard to the workplace would level the playing field for everyone.

Reducing Background Noise: Some Rules of Thumb

Block and dampen unwanted sound to reduce background noise and to increase signal-to-noise ratio. Allowable background noise should be at 35 dB. Some steps that can be taken when building:
• better wall construction
• staggered metal stud system with continuous drywall surface
• use of light gage metal studs which perform better than wood studs
• use of sound attenuation blankets in walls and above lay-in ceilings
• seal/caulk openings, wall penetrations, offset electrical boxes
• use minimum 1" insulated glazing and insulated frame assemblies
• use quiet HVAC systems, locate equipment away from meetings rooms
• avoid use of unit ventilators

Controlling Reverberation

Decrease reverberation time and reduce the reflected sound with diffusive surfaces at ear level.
• Use reflective ceiling above presenter and diffusive materials at side walls and ceiling
• Use absorbent surface materials at rear wall to control late arriving sound
• Use materials that can absorb 50% to 90% of sound with a space
• Match meeting occupants to room size

Responsible Design for a Meeting Room

An ideal meeting room for people who have hearing loss would be in a well constructed building that controls structure and mechanical noise. Some of its features would include:
• Absorption at rear wall to reduce late arriving sound
• Diffusion side walls, especially at hearing level
• Flooring application to control foot fall and noise
• Reflective surface ceiling application above meeting area to support early sound signal
• Low room volume ratio
• Good lighting level

HOH Meeting Strategies

Don concluded his presentation with a discussion about meeting strategies for people with hearing loss. Often there is very little we can do about the acoustics of a room, but here are some strategies that could help overall:
• Establish a sitting arrangement so everyone faces each other
• Establish speaking rules and enforce them
• Have an agenda and stick to it, providing context
• Use "Action Item - Response Item" format
• Track previous meeting minutes
• Repeat questions and comments to make sure you understand what you heard
• Utilize a meeting scribe
• Complete and publish meeting minutes ASAP

Conclusion

During our Q & A session, Don pointed out that it's harder to retrofit than build from scratch, but there are some changes that can be made with little additional costs. Acoustic panels are one possibility; Don passed around samples of acoustic materials that are very sound-absorbent and could be affixed to walls. Carpeting and draperies also help absorb sound in a room, as could the use of cork on walls. Don also mentioned that Classroom Standards are mandated in some states but are voluntary in others.

If you would like more detailed information about acoustics and its challenges for people with hearing loss, you can contact Don at dbataille@swbr.com or don@bataille.us. You can also visit the websites of the Acoustical Society of America at www.asa.aip.org and ASHA at www.asha.org.

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