1. Technology in Architecture
Lecture 19
Sound Privacy
Sound Privacy Enhancement
Sound Privacy Reduction
Structure Borne Sound

2. Sound Privacy

3. Sound Privacy
Privacy is affected by initial sound source, TL, NC and absorbtion
Room A
Room B
SPL
NC1
NC2
Privacy Maintained TL TL
Privacy Violated
Sectional View

4. Sound Privacy—Example 1
Room A: NC500=35
Room B: NC500=25
Room A
Room B
SPL=70
NC1=35
SPL=40
SPL=40
NC2=25
Privacy Maintained
TL=30
TL=30
Privacy Violated
Sectional View

5. Noise Criteria Curves Privacy is affected by background noise level
NC 500 hz
Max SPL500=40 db
S: p. 759, F.17.17

6. Sound Privacy—Example 1
Room A: NC500=35, SPL500 ≤ 40 db
Room B: NC500=25, SPL500 ≤ 31 db
Initial check based on TL alone
Room A
Room B
SPL=70
NC1=35
SPL=40
SPL=40
NC2=25
Privacy Maintained
TL=30
TL=30
Privacy Violated
Sectional View

7. Sound Privacy—Example 1
Combine effect of TL and absorption for final analysis
NR=TL-10 Log (S/AR)
NR: noise reduction (db)
TL: transmission loss (db)
S: area of barrier wall (ft2)
AR: total absorption of receiving room (sabins, ft2)

8. Sound Privacy—Example 1
For each frequency:
If SPL-NR ≤ NCmax privacy achieved
If SPL-NR > NCmax privacy violated

9. Sound Privacy Enhancement

10. Sound Privacy Enhancement
TL data can be enhanced by standard enhancements
Wood stud wall (STC 35)
Add gyp bd to one side +2 db
Add gyp bd to both sides +4 db
Double thickness insulation +6 db
Staggered studs +9 db
Double studs +13 db
from S: p. 816, T.19.1

11. Sound Privacy Reduction

12. Sound Privacy Reduction
Privacy is diminished by flanking noise, weaker STC constructions and/or gaps
S: p. 825, F.19.34

13. Sound Privacy Privacy diminished by weaker STC constructions
S: p. 817, F.19.22

14. Sound Privacy—Example 1
A 100 ft2 wall assembly has TL=50 [excellent]
What is the overall TL if a 20 ft2 door with TL=20 is part of the wall?
S: p. 817, F.19.22

15. Sound Privacy—Example 1
S1= 100 ft2
S2= 20 ft2
S2/S1=20/100=20%
TL1-TL2=50-20=30 db
TL1-TLC=23
TLC=TL1-23=27 db
[fair-poor]
S: p. 817, F.19.22

16. Sound Privacy Privacy diminished by construction gaps
S: p. 817, F.19.23

17. Sound Privacy—Example 2
A 10x10 (100 ft2) wall assembly has TL=35
[very good]
What is the overall TL if a 1/16” gap exists along each vertical edge?
S: p. 817, F.19.23

18. Sound Privacy—Example 2
S1= in2
S2= 15 in2
S2/S1=15/14400=0.1%
TL1=35 db
TLC=29 db
[fair-poor]
S: p. 817, F.19.23

19. Structure-Borne Noise

20. Sound Paths
Structure-Borne Sound
S: p. 806, F.19.10

21. Sound Transmission Reduction
Impact Isolation
Structural isolation
Flexible connections
Spring mounts
Inertial dampening
S: p. 845, F.19.47

22. Sound Transmission Reduction– Floors
Sound Transmission Class (STC)
Impact Isolation Class (IIC)
S: p.1726, Index L.3

23. Impact Isolation Class—Enhancements
Construction Tectonics
S: p. 842, F.19.43

25. Impact Isolation Class—Enhancements
Resilient Floor Finishes:
1/16” vinyl tile 0 db
1/8” linoleum or rubber tile 4 +/- 1 db
¼” cork tile 10 +/- 2 db
Low pile carpet on fiber pad 12 +/- 2 db
Low pile carpet on fiber pad 18 +/- 3 db
High pile carpet on foam pad 24 +/- 3 db
from S: p. 843

26. Mechanical Isolation
Moving parts (vibration sources) eliminated by mechanical isolation
S: p. 851, F.19.54