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Lecture 19

Sound PrivacySound Privacy Enhancement

Sound Privacy ReductionStructure Borne Sound

Lecture 19

Sound PrivacySound Privacy Enhancement

Sound Privacy ReductionStructure Borne Sound

Sound PrivacySound PrivacySound PrivacySound Privacy

Sound PrivacySound PrivacyPrivacy is affected by initial sound source, TL, NC and absorbtion

Privacy Maintained Privacy Violated

NC2

SPL

NC1

TL TL

Room A Room B

Sectional View

Sound Privacy—Example 1Sound Privacy—Example 1

Room A: NC500=35

Room B: NC500=25

Privacy Maintained Privacy Violated

NC2=25

SPL=70

NC1=35

TL=30 TL=30

Room A Room B

Sectional View

SPL=40SPL=40

Noise Criteria CurvesNoise Criteria Curves

Privacy is affected by background noise level

NC 35 @ 500 hz

Max SPL500=40 db

S: p. 759, F.17.17

Sound Privacy—Example 1Sound Privacy—Example 1

Room A: NC500=35, SPL500 ≤ 40 db

Room B: NC500=25, SPL500 ≤ 31 db

Initial check based on TL alone

Privacy Maintained Privacy Violated

NC2=25

SPL=70

NC1=35

TL=30 TL=30

Room A Room B

Sectional View

SPL=40SPL=40

Sound Privacy—Example 1Sound 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)

Sound Privacy—Example 1Sound Privacy—Example 1

For each frequency:

If SPL-NR ≤ NCmax privacy achieved

If SPL-NR > NCmax privacy violated

Sound Privacy EnhancementSound Privacy EnhancementSound Privacy EnhancementSound Privacy Enhancement

Sound Privacy EnhancementSound Privacy EnhancementTL 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

Sound Privacy ReductionSound Privacy ReductionSound Privacy ReductionSound Privacy Reduction

Sound Privacy ReductionSound Privacy Reduction

Privacy is diminished by flanking noise, weaker STC constructions and/or gaps

S: p. 825, F.19.34

Sound PrivacySound Privacy

Privacy diminished by weaker STC constructions

S: p. 817, F.19.22

Sound Privacy—Example 1Sound 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

Sound Privacy—Example 1Sound 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

Sound PrivacySound Privacy

Privacy diminished by construction gaps

S: p. 817, F.19.23

Sound Privacy—Example 2Sound 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

Sound Privacy—Example 2Sound Privacy—Example 2

S1= 14400 in2 S2= 15 in2

S2/S1=15/14400=0.1%

TL1=35 db

TLC=29 db

[fair-poor] S: p. 817, F.19.23

Structure-Borne NoiseStructure-Borne NoiseStructure-Borne NoiseStructure-Borne Noise

Sound PathsSound PathsStructure-Borne Sound

S: p. 806, F.19.10

Sound Transmission Sound Transmission ReductionReduction

Impact Isolation

Structural isolation

Flexible connections

Spring mounts

Inertial dampening

S: p. 845, F.19.47

Sound TransmissionSound TransmissionReduction– Floors Reduction– Floors Sound Transmission Class (STC)

Impact Isolation Class (IIC)

S: p.1726, Index L.3

Impact Isolation Class—Impact Isolation Class—Enhancements Enhancements

Construction Tectonics

S: p. 842, F.19.43

Impact Isolation Class—Impact Isolation Class—Enhancements 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

Mechanical IsolationMechanical Isolation

Moving parts (vibration sources) eliminated by mechanical isolation

S: p. 851, F.19.54