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Technology in Architecture

Technology in Architecture. Lecture 14 Noise Reduction by Absorption Sound Paths Sound Isolation. Noise Reduction by Absorption. Noise Reduction by Absorption. Increased absorption reduces ambient noise. S: p. 761, F.18.2. Noise Reduction by Absorption. 69 db.

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Technology in Architecture

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  1. Technology in Architecture Lecture 14 Noise Reduction by Absorption Sound Paths Sound Isolation

  2. Noise Reduction by Absorption

  3. Noise Reduction by Absorption Increased absorption reduces ambient noise S: p. 761, F.18.2

  4. Noise Reduction by Absorption 69 db Reverberation increases ambient sound levels S: p. 788 F.19.1

  5. Sound Paths

  6. Sound Paths Air-Borne Sound Structure-Borne Sound S: p. 796, F.19.10

  7. Sound Transmission Barriers reduce sound transmission to reduce noise intrusion S: p. 797, F.19.11

  8. Air-Borne Sound Transmission Loss (TL): sound energy lost through a construction assembly S: p. 803, F.19.17

  9. Noise Reduction Combined effect of TL and absorption 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)

  10. Noise Reduction Example What is the noise reduction at 500 hz between two rooms separated by a 2x4 stud wall with ½” gyp. bd. on each side. Receiving room absorption: 450 sabins, ft2 Separation wall: 10’ x 20’

  11. Noise Reduction Example Find TL500 TL500=35 db S: p. 803, F.19.17

  12. Noise Reduction Example Find NR500 NR500=TL500-10 Log (S/AR) =35-10 Log (200/450) =35-10 Log (0.444) =35-10(-0.35) =35+3.5=38.5 say 39db

  13. Sound Isolation

  14. Sound Transmission Class Sound Transmission Class (STC): defines overall transmission loss across center band frequencies Barrier STC Descriptor/ Application Ranking 25 Poor/1 Space divider 30 Fair/2 Room divider 35 Very Good/4 Offices near quiet space 42-45 Excellent/5 Party walls 46-50 Total Privacy/6 Quiet next to noisy from S: p. 818. T.19.6

  15. Sound Transmission Class STC can be compromised by: • Combination with lesser sound barriers • Gapsin construction “An air path is a good sound path”

  16. Sound Transmission Class STC of a wall assembly 2x4 stud with gyp. Bd. S: p.1674, Index K.1

  17. Sound Transmission Class Wall assembly description 2x4 stud with gyp. bd. S: p. 1678, Table K.1

  18. Sound Transmission Class Wall assembly selection TL data 2x4 stud with gyp. bd. S: p. 1675, Index K.2

  19. Sound Transmission Class Floor assembly follows same process S: p. 1686, Index L.1

  20. Noise Criteria Noise Criteria (NC): accepted noise level for a given space. Defined for center band frequencies 62.5 125 250 500 1000 2000 4000

  21. Noise Criteria Curves Accepted noise level for a given space. S: p. 749, F.17.17

  22. Noise Criteria Noise Criteria for various applications S: p.821, T.19.8

  23. Room Criteria Room Criteria (RC(x)): accepted noise level for a given space. Defined for NC frequencies plus extremely low frequencies (~16 and 31.5 hz) Beginning to replace NC curves in practice

  24. Room Criteria Curves Room Criteria accepted noise level for a given space. S: p. 751, F.17.18

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