Download presentation

Presentation is loading. Please wait.

Published byJustina Austin Modified over 2 years ago

1
Technology in Architecture Lecture 17 Sound in Enclosed Spaces Reverberation Auditorium Design Lecture 17 Sound in Enclosed Spaces Reverberation Auditorium Design

2
Sound In Enclosed Spaces

3
Sound Absorption Amount of sound energy not reflected S: p. 771,, F.18.2

4
Sound Absorption Absorption coefficient α=I α /I i α=absorption coefficient I α =sound power intensity absorbed (w/cm 2 ) I i =sound power impinging on material (w/cm 2 ) 1.0 is total absorption

5
Sound Absorption Absorption coefficient S: p. 769, T.18.1

6
Sound Absorption Absorption A=Sα A=total absorption (sabins) S=surface area (ft 2 or m 2 ) α=absorption coefficient sabins (m 2 )= 10.76 sabins (sf)

7
Sound Absorption Total Absorption Σα=S 1 α 1 + S 2 α 2 + S 3 α 3 +…+S n α n or ΣA=A 1 + A 2 + A 3 +…+A n

8
Sound Absorption Average Absorption α avg =ΣA/S α avg <0.2 “live” α avg >0.4 “dead” S: p. 774, F.18.6

9
Reflection in enclosed spaces Acoustical phenomena S: p. 787, F.18.20 S: p. 788, F.18.21

10
Ray diagrams Trace the reflection paths to and from adjoining surfaces angle of incidence = angle of reflection I R

11
Ray diagrams Trace the reflection paths to receiver Reflected sound path ≤ Direct sound path+55 Note: check rear wall and vertical paths Note: SR-6=RR-7 SR-6: p.116, F.5-12

12
Reflection in enclosed spaces Auditorium sound reinforcement S: p. 789, F.18.23

13
ReverberationReverberation

14
Reverberation Persistence of sound after source has ceased S: p. 771, F.18.2

15
Reverberation Time Period of time required for a 60 db drop after sound source stops T R = K x V/ΣA T R : reverberation time (seconds) K: 0.05 (English) (0.049 in SR-6) or 0.16 (metric) V: volume (ft 3 or m 3 ) ΣA: total room absorption, sabins (ft 2 or m 2 )

16
Reverberation Time Application Volume S: p. 782, F.18.13 ft 3 x1000 3.5 35.0 350

17
Reverberation Time Calculated for “center band frequencies” 125250500100020004000 Pay specific attention to 125 hz and 500 hz

18
Reverberation Example Compile data Material Absorption Coefficient Material Surface Area SR-6: p.121

19
Reverberation Example Compare to requirements and adjust S: p. 782, F.27.13 ft 3 x1000 3.5 35.0 350

20
Auditorium Design

21
Room Acoustics Noise ControlSound System

22
Auditorium Design Factors Audience Size Range of Performance Activities Audience Sophistication

23
Auditorium Design Parameters 1. Audience Size (floor area): 6-8sf/seat 2. Reverberation (volume): Motion Picture Theatre100 cf/seat Lecture Hall100 cf/seat Music Room/Auditorium200-250 cf/seat Symphony Hall200-300 cf/seat Choral Rehearsal350 cf/seat Band Rehearsal500 cf/seat

24
Auditorium Design Parameters 3. Ceiling Height= Volume/Floor Area generally…20 x T R

25
Auditorium Design Parameters 4. Typical Dimensions L:W:H = 2H:1.5H:H Determine acceptable width (80-120’) Determine length (L = SF/Width) If Length ≥120’, use balcony

26
Auditorium Design Parameters 5. Stage opening: 40-50’ wide x 25’ high

27
Auditorium Design Parameters 6. Shape Walls and Ceilings a) source is 5’ from stage front, 5’ above stage floor b) trace reflectances from back wall, side walls, and ceiling @ 40-60’ from stage 40’ 60’

28
Auditorium Design Parameters 7. Check Echoes

29
Auditorium Design Example Given data RR-7: p.119

30
Reverberation Time Symphonic 492,480 ft 3 T R =1.5 seconds S: p. 782, F.18.13 ft 3 x1000 3.5 35.0 350

31
Auditorium Design Example Given data SR-6: p.115, F.5-11

32
Auditorium Design Example Given data SR-6: p.116, F.5-12

33
Auditorium Design Example Area takeoffs SR-6: p.120

34
Auditorium Design Example Locate coefficients S: p. 769, T.18.1

35
Auditorium Design Example Absorption Coefficients SR-6: p.121

36
Auditorium Design Example Compute absorption Compute reverberation SR-6: p.121

37
Auditorium Design Example Compute T R 500 for given data: T R =0.049 x V/ ΣA =0.049 x 492,480/12,538 =1.92 seconds

38
Auditorium Design Example Compute absorption needed for volume: T R =1.5 seconds ΣA=0.049 x V/T R =0.049 x 492,480/1.5 =16,088 sabins

39
Auditorium Design Example Adjust to meet absorption Add acoustical tile on walls

40
Auditorium Design Example Determine acoustical tile area

41
Auditorium Design Example Determine acoustical tile area Sabins design16,088 - Sabins given12,538 Sabins short 3,550 Translate to area of acoustical tile Sabins/Δα=3,550/0.67= 5,299 sf

42
Auditorium Design Example Add 5,299 sf of acoustical tile on walls Recompute T R500

43
Auditorium Design Example Recompute T R-500 for revised data: T R-500 =0.049 x V/ ΣA =0.049 x 492,480/16,088 =1.5 seconds Compute T R-125 for revised data: T R-125 =0.049 x V/ ΣA =0.049 x 492,480/9,593 =2.52 seconds

44
Auditorium Design Example Compare T R-500 with T R-125 : T R - 125 /T R - 500 =2.52/1.5= 1.68 Ratio should be 1.6-1.85 to offset hearing deficiency

45
Auditorium Design Example Check final conditions SR-6: p. 122

46
Sound Systems Check final conditions S: p. 794, F.18.28

Similar presentations

OK

Reflection and Mirrors. Reflection Reflection: The bouncing back of a particle or wave that strikes the boundary b/w 2 media. Waves reflect in straight.

Reflection and Mirrors. Reflection Reflection: The bouncing back of a particle or wave that strikes the boundary b/w 2 media. Waves reflect in straight.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on job evaluation and job rotation Ppt online shopping project in html Ppt on articles of association pdf Ppt on water pollution Ppt on reflection and refraction of light Ppt on industrial development in gujarat ahmedabad A ppt on leadership Ppt on the art of warfare Ppt on index numbers definition Ppt on necessity is the mother of invention