Basic Documentation
Table Of Contents
- About this Application Guide
- Chapter 1–Introduction
- Chapter 2–Physics of Sound
- Chapter 3–HVAC Sound Sources
- Chapter 4–HVAC Sound Attenuation
- Introduction to HVAC Sound Attenuation
- Plenums
- Duct Attenuation
- Duct Takeoffs and Divisions
- Duct Silencers
- End Reflection
- Environment Adjustment Factor
- Space Effect
- Radiated Sound Attenuation
- Chapter 5–HVAC System Sound Analysis
- Chapter 6–Minimizing HVAC Sound
- Appendix
- Glossary
- Index
Chapter 2–Physics of Sound
(See the Appendix for a copy of this graph that is suitable for reproduction.)
Figure 6. Room Criterion Curves.
Determining an RC Rating
To determine what RC rating should be applied to an existing room, follow the steps listed
below.
Step 1. Measure Existing Sound Pressure
Measure the existing sound pressure level in the room in decibels at all of the octave band
center frequencies. Calculate an average dB value from the room dB values obtained at 500,
1,000, and 2,000 Hz.
Step 2. Mark Average Sound Pressure
Mark the average obtained in Step 1 on an RC Criterion graph on the 1,000 Hz vertical scale.
Create an RC reference curve by drawing a line through this point that parallels the standard
RC curves. (Note that the standard slope of an RC curve is a loss of 5 dB per frequency band
as it goes from left to right.)
20 Siemens Building Technologies, Inc.