Acoustic Ni Bien And Joel

ACOUSTIC DESIGN COMPUTATION Type of Hall:

Chapel

Place:

San Cirilo Pasacao, Camarines Sur

Dimensions:

Volume = LxWxH

Calculations: Length = 10.4 m Width = 11.75 m Height = 2.3 m Volume: V = LxWxH V = 10.4x11.75x2.3 V = 281.06 m3 In feet:

.

V = 281.07

3 3 3.28 𝑓𝑡 m ( 1𝑚 )

V = 922.113 ft3

Reverberation Time (RT):

RT =

0.049V S1a1+S2a2+S3a3+⋯Snan

Where: 0.049 = constant (unit correction) Sn = surface area (ft2) an = Absorption Coefficient (unit less)

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V = Volume (ft3) Computation for Walls, floor and ceiling:  For Front View : Absorptive and Reflective Materials: Concrete (painted) and Ply wood Paneling.

Table 1 Absorption Coefficients for Front Side Reflective Materials

Absorption Coefficients 250 Hz 0.05 0.4

Painted Concrete Ventilated grills door

500 Hz 0.06 0.5

1000 Hz 0.07 0.5

Area of Rectangle (Painted Concrete): h = 2.3m

In Feet:

L = 10.4m

S = (23.92m2)

(

3.28ft 2

)

1m

S= 10.4 x 2.3m

S = 257.4727 ft3

S = 23.92 m2 Product of S and a for 250Hz:

For 500 Hz.:

Sa = (257.4727ft2)(0.05)

Sa = (257.4727ft2)(0.06)

Sa = 12.8736369 sabines

Sa = 15.44836423 sabines

For 1000 Hz. Sa = (257.4727ft2)(0.07) Sa = 18.0230916 sabines

Area of Ventilated grills door:

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L = 1.5 m

h = 2m

S = 1.5m x 2m

S = 3m2 In Feet: S = (3m2)(

3.28ft

)

2

1m S = 32.29173 ft2

Product of S and a for 250 Hz:

For 500 Hz:

Sa = 32.29173 x 0.4

Sa = 32.29173 x 0.5

Sa = 12.9166925 sabines

Sa = 16.14586563 sabines

For 1000 Hz. Sa = 32.29173 x 0.5 Sa = 16.1458656 sabines

Area of painted concrete L = 10.4m – 1.5m L = 8.9m h = 2.3 – 2 h = 0.3 m S = 8.9m x 0.3m S = 2.67 m2 In Feet: S = (2.67m2)

(

3.28ft 2

)

1m

S = 8.75984252 ft2 xxi

Product of S and a for 250 Hz:

For 500 Hz:

Sa = (8.75984252) (0.05)

Sa = (8.75984252) (0.06)

Sa = 0.437992126 sabines

Sa = 0.5255905512 sabines

For 1000 Hz. Sa = (8.75984252) (0.07) Sa = 0.6131889764 sabines

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For the left side wall: Absorptive and reflective materials: Painted concrete, Ventilated grill

Table 2 Absorption Coefficients for left Side Reflective Materials

Absorption Coefficients 250 Hz 0.05 0.4

Printed Concrete Ventilated Grill

500 Hz 0.06 0.5

1000 Hz 0.07 0.5

Area of Window (Ventilated Grill):

Area of Printed Concrete:

L = 1.55 m;

w =11.75 m;

h = 1.25 m

S = (1.55)(1.25) = 1.9375 m2

S = (11.75)(2) = 23.5 m2

In Feet: S=

(1.9m2) (

h=2m

In Feet: 3.28ft 2

)

S=

(23.5m2) (

1m

S2 = 252.9519 ft2

For 3 windows S= 20.85508 (3) S = 62 .56524 ft2 For window

Sa= 62 .56524 x 0.4

)

1m

S1 = 20.85508 ft2

Product of S and a for 250Hz

3.28ft 2

for 500Hz Sa = 62 .56524 0.5

Sa = 25.026096 sabines Sa = 31.28262 sabines for 1000Hz Sa = 62 .56524 x 0.5 xxiii

Sa = 31.28262 sabines For Printed concrete Product of S and a for 250Hz

for 500Hz

Sa = 252.9519 x 0.05

Sa = 252.9519x 0.06

Sa = 12.6475947 sabines

Sa = 15.17711369 sabines

for 1000Hz Sa = 252.9519x 0.07 Sa = 17.7066326 sabines For painted concrete and ventilated grill windows: S = 252.9519 - 62 .56524 = 190.38676 ft2 Product of S and a for 250Hz

for 500Hz

Sa = 190.38676 x 0.05

Sa = 190.38676 x 0.06

Sa = 9.519338 sabines

Sa = 11.4232056 sabines

for 1000Hz Sa = 190.38676 x 0.07 Sa = 13.3270732 sabines

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 For the right side wall: Absorptive and reflective materials: drapery and wood parquet

Table 3 Absorption Coefficients for Right Side Reflective Materials

Absorption Coefficients 250 Hz 0.05 0.4

Printed Concrete Ventilated Grill

Area of Window (Ventilated Grill): L = 1.55 m;

500 Hz 0.06 0.5

Area of Printed Concrete:

h = 1.25 m

w =11.75 m;

S = (1.55) (1.25) = 1.9375 m2

h=2m

S = (11.75) (2) = 23.5 m2

In Feet:

In Feet: 2

S = (1.9m2) 3.28ft

(

1000 Hz 0.07 0.5

S=

(23.5m2) (

3.28ft2

)

1m

)

1m

S1 = 20.85508 ft2

S2 = 252.9519 ft2

For 3 windows S= 20.85508 (3) S = 62 .56524 ft2

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For window Product of S and a for 250Hz

for 500Hz

Sa= 62 .56524 x 0.4

Sa = 62 .56524 0.5

Sa = 25.026096 sabines

Sa = 31.28262 sabines

for 1000Hz Sa = 62 .56524 x 0.5 Sa = 31.28262 sabines For Printed concrete Product of S and a for 250Hz

for 500Hz

Sa = 252.9519 x 0.05

Sa = 252.9519x 0.06

Sa = 12.6475947 sabines

Sa = 15.17711369 sabines

for 1000Hz Sa = 252.9519x 0.07 Sa = 17.7066326 sabines For painted concrete and ventilated grill windows: S = 252.9519 - 62 .56524 = 190.38676 ft2 Product of S and a for 250Hz

for 500Hz

Sa = 190.38676 x 0.05

Sa = 190.38676 x 0.06

Sa = 9.519338 sabines

Sa = 11.4232056 sabines

for 1000Hz Sa = 190.38676 x 0.07 Sa = 13.3270732 sabines

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 For the Floor: Absorptive and reflective materials: Marble tiles

Table 4 Absorption Coefficients for the floor Reflective Materials

Absorption Coefficients 250 Hz 0.1

Marble Tiles

Area of Floor (Marble Tiles): L = 11.75 m; h = 10.4m S = (11.75) (10.4) = 122.2 m2 In Feet: S = (122.2 m2 ) (3.28ft)2 S = 1315.35 ft2 Product of S and a for 250Hz Sa= 1315.35 x 0.1 Sa = 131.534985 sabines

for 500Hz Sa = 1315.35 x 0.1 Sa = 131.534985 sabines

for 1000Hz Sa = 1315.35 x 0.1 Sa = 131.534985 sabines

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500 Hz 0.1

1000 Hz 0.1

 For the ceiling: Absorptive and reflective materials: plywood paneling

Table 5 Absorption Coefficients for the ceiling Reflective Materials

Absorption Coefficients 250 Hz 0.22

Plywood paneling

Area of the ceiling(wood): L = 11.75 m; h = 10.4m S = (11.75) (10.4) = 122.2 m2 In Feet: S = (122.2 m2 ) (3.28ft)2 S = 1315.35 ft2

Product of S and a for 250Hz Sa= 1315.35 x 0.22 Sa = 289.376968 sabines

for 500Hz Sa = 1315.35 x 0.17 Sa = 223.609475 sabines

for 1000Hz Sa = 1315.35 x 0.09 Sa = 118.381487 sabines

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500 Hz 0.17

1000 Hz 0.09

Summary of Reflective Materials

For the Computation of the Seats and Audience : Maximum number of 50. Table 7 Absorption Coefficients for Seats and audience Materials 250 Hz 500 Hz Seats (fabric-upholsterd, 0.66 0.8 empty) Seats (fabric-upholsterd, fully 0.74 0.88 occupied) People-adults (per 1/10 0.35 0.42 person) Computation for the absorption of empty Seats at 250 Hz A = 50 x 0.66 A = 33 sabines Computation for the absorption of empty Seats at 500 Hz A = 50 x 0.8 A = 40 sabines Computation for the absorption of empty Seats at 1000 Hz A = 50 x 0.88 A = 44 sabines

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1000 Hz 0.88 0.96 0.46

Computation for the absorption of Seats that is 25% occupied at 250 Hz

A = (400 x10 x 0.25 x 0.35) + A(empty) A = (400 x10 x 0.25 x 0.35) + 33 A = 383 sabines Computation for the absorption of Seats that is 75% occupied at 250 Hz

A = (400 x 10 x 0.75 x 0.35) + A(empty) A = (400 x 10 x 0.75 x 0.35) + 33 A = 1083 sabines Computation for the absorption of Seats that is 100% occupied at 250 Hz A = 50 x 0.74 A = 37 sabines

Computation for the absorption of Seats that is 25% occupied at 500 Hz

A = (400 x 10 x 0.25 x 0.42) + A(empty)

A = (400 x 10 x 0.25 x 0.42) + 37 A = 457 sabines Computation for the absorption of Seats that is 75% occupied at 500 Hz A = (400 x 10 x 0.75 x 0.42) + A(empty) A = (400 x 10 x 0.75 x 0.42) + 37 A = 1297 sabines

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Computation for the absorption of Seats that is 100% occupied at 500 Hz A = 50 x 0.88 A = 44 sabines

Computation for the absorption of Seats that is 25% occupied at 1000 Hz

A = (400 x 10 x 0.25 x 0.46) + A(empty) A = (400 x 10 x 0.25 x 0.46) + 44

A = 504 sabines Computation for the absorption of Seats that is 75% occupied at 1000 Hz

A = (400 x 10 x 0.75 x 0.46) + A(empty) A = (400 x 10 x 0.75 x 0.46) + 44

A = 1424 sabines Computation for the absorption of Seats that is 100% occupied at 1000 Hz A = 50 x 0.96 A =48 sabines

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Table 8. Summary of Absorption Coefficient for Seats Absorption Coefficients(sabines) 250 Hz 500 Hz 1000 Hz Considering empty seats/no 33 40 44 audience Considering 25% attendance 383 457 504 Considering 75% attendance 1083 1297 1424 Considering 100% attendance 37 44 48 Computation for Reverberation Time: For 250Hz: 250 Hz Considering empty seats:

RT = 0.049(922.113) 403.388307+ 33

RT = 0.1035397518 seconds Considering 25% attendance:

RT = 0.049(922.113) 403.388307+ 383

RT = 0.05745703058 seconds Considering 75% attendance:

RT = 0.049(922.113) 403.388307+ 1083

RT = 0.03039820536 seconds Considering 100% attendance:

RT = 0.049(922.113) 403.388307+ 37

RT = 0.1025993113 seconds xxxiv

For 500Hz: Considering empty seats: RT= 0.049(922.113) 495.106511+ 40 RT = 0.08443839884 seconds Considering 25% attendance:

RT= 0.049(922.113) 495.106511+ 457

RT = 0.04745638905 seconds Considering 75% attendance:

RT = 0.049(922.113) 495.106511+ 1297

RT = 0.02521252879 seconds Considering 100% attendance:

RT = 0.049(922.113) 495.106511+ 44

RT = 0.0838118926 seconds For 1000Hz: Considering empty seats:

RT = 0.049(922.113) 400.087015 + 44 RT = 0.1017447831 seconds xxxv

Considering 25% attendance:

RT = 0.049(922.113) 400.087015 + 504

RT = 0.04997697816 seconds Considering 75% attendance:

RT = 0.049(922.113) 400.087015 + 1424

RT = 0.2477044943 seconds Considering 100% attendance:

RT = 0.049(922.113) 400.087015 + 48

RT = 0.1008365239 seconds

Table 9. Summary of Reverberation Time Reverberation Time(seconds) 250 Hz 500 Hz 1000 Hz Considering empty seats/no audience 0.104 0.084 0.103 Considering 25% attendance 0.057 0.047 0.050 Considering 75% attendance 0.030 0.025 0.248 Considering 100% attendance 0.103 2.37 0.101

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