From our geographically central location, Soundscape Engineering LLC's acoustical consultants and noise and vibration control engineers serve clients located throughout North America - in Chicago, Illinois; Detroit, Grand Rapids, Lansing, Ann Arbor, and Petoskey, Michigan; Milwaukee and Madison Wisconsin; Indianapolis, Fort Wayne, South Bend, and Northwest Indiana; Los Angeles, California; Vancouver, British Columbia; Dayton and Cincinnati Ohio, Winnipeg Manitoba; Saskatoon and Regina Saskatchewan; and elsewhere. Our engineers consult on issues of room acoustics, sound isolation, speech privacy, HVAC noise control, building vibration, and exterior noise impact. They also provide acoustic and vibration measurement services.

News & Editorials

Soundscape Engineering's latest news,tips, and trends in the acoustic engineering and consulting trade.

  • Home
    Home This is where you can find all the blog posts throughout the site.
  • Categories
    Categories Displays a list of categories from this blog.
  • Tags
    Tags Displays a list of tags that have been used in the blog.
  • Bloggers
    Bloggers Search for your favorite blogger from this site.
  • Login

Speech Privacy for Psychiatric Offices

Posted by on in Uncategorized
  • Font size: Larger Smaller
  • Subscribe to this entry
  • Print

For the past 15 minutes, you and your spouse have been sitting comfortably in your psychiatrist’s office, uncomfortably discussing the details of your marriage. You’ve been aware of someone talking in the adjacent psychiatric office, but only as a background mumbling. Until now, it wasn’t distracting. Now the person is loud and emotional. His words have become easily audible and it is very distracting; not just because you can understand what he is saying, but because you recognize that it is the voice of a work colleague! Speech privacy is an important design parameter for psychiatric offices.

During my career as an acoustical consultant, I have been asked to consult on the design of new psychiatric offices and to assist in fixing sound isolation problems at existing offices. The primary factors that determine the level of speech privacy between offices are the voice effort (i.e., how loud the person talks), the sound isolating performance of the demising wall, and the level of background noise. To a lesser degree, room finishes, orientation of the talker to the demising wall, and familiarity with the talker are factors.

There are several measures of speech privacy, including Articulation Index (AI), Sound Transmission Index (STI), Privacy Index (PI), and Speech Intelligibility Index (SII). Subjective descriptions, such as Normal, Confidential, and Secure are associated with each of these objective measures. The "Sound & Vibration Design Guidelines for Health Care Facilities" white paper, which is the acoustical reference for the FGI/ASHE 2010 Guide for the Design and Construction of Healthcare Facilities, calls for psychiatric offices to have a Confidential level of speech privacy. Measuring speech privacy in a constructed facility is relatively straight forward and accurate. Predicting speech privacy during design is possible, but less accurate. A simple rule of thumb presented in the "Sound & Vibration Design Guidelines for Health Care Facilities" is that the sum of the partition STC and the background noise level (measured in A-weighted decibels) must be at least 75 in order to achieve a Confidential level of speech privacy. I recommend that a more detailed calculation be performed whenever possible. What this rule of thumb does emphasize is the importance of the background noise level.

Architects are accustomed to specifying wall STC, but many forget that background noise level is just as important as the partition STC. Background noise is typically dominated by the heating and air-conditioning system. However, many HVAC systems do not operate 100% of the time and therefore cannot be relied on to provide a consistent level of background noise. In these situations, I recommend that an electronic sound masking system be considered. These systems can be set to produce a consistent, low level of background noise. In the absence of a consistent level of background noise, demising partitions must be over-designed.

Whether you’re located in Chicago or elsewhere, if you are designing new psychiatric offices or have a speech privacy problem with existing offices and would like to work with an acoustical consultant, you can contact me at Soundscape Engineering (