Basic Documentation

RC Curves
• If an identifiable predominant tone exists in the sound (such as, clicking, whining,
whistle, etc.), a T is also added to the above suffix.
• If excessive vibration is present, a V suffix is also added to the above.
Figure 6 shows the standard family of Room Criterion curves. Table 4 lists specific
applications and the maximum acceptable sound criterion that apply when referencing these
curves. Note that the Criterion level is always the dB level of the particular RC curve as it
passes through 1,000 Hz.
Utilizing the NC curves for design purposes typically results in background sound
characteristics having a noticeable rumble or hiss. Although the dB level may be acceptable
for speaking, the overall sound profile is less likely to be as acceptable as a design that is
based upon the RC Criterion.
Table 4. Applicable NC and RC Sound Criterion Curves for Various Applications.
Application Criterion Level
General Office 35 - 40
Private Office 30 - 35
Conference Room 25 - 30
Corridors 40 - 45
Hospital Room 25 - 30
Surgical Room 30 - 35
Classroom 25 - 35
Cafeteria 45 - 50
Library 30 - 40
Lobby 40 - 45
Auditorium 25 - 30
Washroom 40 - 50
Research Laboratory 35 - 45
Educational Laboratory 35 - 40
Sound Studio 15 - 20
Siemens Building Technologies, Inc. 19