If I can hear you, you must be able to hear me… Right?
Of the many issues I have encountered in office design, one of the least understood (and most critical to tenant satisfaction) is sound control.
The impression I get from most prospective tenants is that they think you either have sound privacy, or you don’t. Most don’t understand that it is measured in degrees of sound deadening (or attenuation).
Many times I hear the comment, “I can hear the people on the other side of the wall, so they must be able to hear me, as well”. Although this is probable, it is not always true. And just how serious an issue this might prove to be depends upon the reason for the need for sound privacy.
The two main objectives of sound privacy are:
- The protection of confidential information
- The elimination of distracting sounds
“In general, loud speech can be understood fairly well through an STC 30 wall but should not be audible through an STC 60 wall. An STC of 50 is a common building standard and blocks approximately 50 dB from transmitting through the partition. However, occupants could still be subject to awareness, if not understanding, of loud speech. Constructions with a higher STC (as much as 10dB better – STC 60) should be specified in sensitive areas where sound transmission is a concern.” – (Source: STCratings.com)
As a general rule, about every 5 STC points equate to a noticeable difference in sound transmission, and a change of about 10 STC equates to a reduction (or addition) in sound to about half (twice) as loud.
First, let me say that I have an educated knowledge of acoustics and sound attenuation, but am not an acoustic engineer or expert. For real design analysis and engineered solutions, I hire acoustic consultants. But for the average office environment sound issues, I have a great deal of experience with proven solutions.
To explain briefly, sound attenuation is the reduction of the sound level, measured in decibels, from a source to a target or subject. To attenuate sound between the source and the target is achieved by either absorbing or blocking the sound. In addition, care needs to be taken to reduce or eliminate flanking and/or penetrations in the partition separating the source from the target. Flanking will typically take place over the top of walls which do not extend to the structural deck or where they abut windows at the exterior of the building.
The effectiveness of the material to reduce sound is a direct factor of the amount of material, its density, thickness, and therefore the physical size of the sound wavelength it is able to block, or its ability to absorb the sound waves. Some materials can block high frequency sound effectively, but be totally ineffective at blocking lower frequency sound. The best solutions provide attenuation across the broad spectrum of sound frequencies. And, care should be taken to consider the entire envelope of a space when considering its sound privacy, including doors, borrowlites, ventilation diffusers, etc.
The Good News: Many proven technologies are out there, and whether constructing new space or retrofitting existing space, simple, inexpensive and effective solutions to sound attenuation are readily available.
Henty+Pfaff & Associates, Architects can help you work out the sound privacy issues in your next space planning project.