BULACAN STATE UNIVERSITYMalolos City, Bulacan

COLLEGE OF ENGINEERINGDepartment of Electronics Engineering

ACOUSTICS DESIGN

Submitted by:

De Leon, Jonel DC.Dela Cruz, Edison E.

Rivera, Michelle AnneMendoza, Ma. Lourdes M.

Umali, Ervin

Submitted to:

Engr. Marian BorjaInstructor

Date of Submission:

1 March 2010

Classroom Location and Room NumberBulacan State University, College of Engineering, Room: E101

Pictures while Measuring the Room

AutoCAD Layout of the Room and Dimensions

CEILING

Absorption coefficients of common building materials and finishes

Floor Materials 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hzconcrete or tile 0.01 0.01 0.15 0.02 0.02 0.02linoleum/vinyl tile on concrete 0.02 0.03 0.03 0.03 0.03 0.02wood on joists 0.15 0.11 0.10 0.07 0.06 0.07parquet on concrete 0.04 0.04 0.07 006 0.06 0.07carpet on concrete 0.02 0.06 0.14 0.37 0.60 0.65carpet on foam 0.08 0.24 0.57 0.69 0.71 0.73

Wall Materials 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 HzBrick: unglazed 0.03 0.03 0.03 0.04 0.05 0.07Brick: unglazed & painted 0.01 0.01 0.02 0.02 0.02 0.03Concrete block – coarse 0.36 0.44 0.31 0.29 0.39 0.25Concrete block – painted 0.10 0.05 0.06 0.07 0.09 0.08Curtain: 10 oz/sq yd fabric molleton 0.03 0.04 0.11 0.17 0.24 0.35Curtain: 14 oz/sq yd fabric molleton 0.07 0.31 0.49 0.75 0.70 0.60Curtain: 18 oz/sq yd fabric molleton 0.14 0.35 0.55 0.72 0.70 0.65Fiberglass: 2” 703 no airspace 0.22 0.82 0.99 0.99 0.99 0.99Fiberglass: spray 5” 0.05 0.15 0.45 0.70 0.80 0.80Fiberglass: spray 1” 0.16 0.45 0.70 0.90 090 0.85Fiberglass: 2” rolls 0.17 0.55 0.80 0.90 0.85 0.80Foam: Sonex 2” 0.06 0.25 0.56 0.81 0.90 0.91Foam: SDG 3” 0.24 0.58 0.67 0.91 0.96 0.99Foam: SDG 4” 0.33 0.99 0.84 0.99 0.98 0.99Foam: polyur. 1” 0.13 0.22 0.68 1.00 0.92 0.97Foam: polyur. ½” 0.09 0.11 0.22 0.60 0.88 0.94Glass: ¼” plate large 0.18 0.06 0.04 0.03 0.02 0.02Glass: window 0.35 0.25 0.18 0.12 0.07 0.04Plaster: smooth on tile/brick 0.013 0.015 0.02 0.03 0.04 0.05Plaster: rough on lath 0.02 0.03 0.04 0.05 0.04 0.03Marble/Tile 0.01 0.01 0.01 0.01 0.02 0.02Sheetrock ½” 16” on center 0.29 0.10 0.05 0.04 0.07 0.09Wood: 3/8” plywood panel 0.28 0.22 0.17 0.09 0.10 0.11

Ceiling Materials 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 HzAcoustic Tiles 0.05 0.22 0.52 0.56 0.45 0.32Acoustic Ceiling Tiles 0.70 0.66 0.72 0.92 0.88 0.75Fiberglass: 2” 703 no airspace 0.22 0.82 0.99 0.99 0.99 0.99Fiberglass: spray 5” 0.05 0.15 0.45 0.70 0.80 0.80Fiberglass: spray 1” 0.16 0.45 0.70 0.90 0.90 0.85Fiberglass: 2” rolls 0.17 0.55 0.80 0.90 0.85 0.80Wood 0.15 0.11 0.10 0.07 0.06 0.07Foam: Sonex 2” 0.06 0.25 0.56 0.81 0.90 0.91Foam: SDG 3” 0.24 0.58 0.67 0.91 0.96 0.99Foam: SDG 4” 0.33 0.90 0.84 0.99 0.98 0.99Foam: polyur. 1” 0.13 0.22 0.68 1.00 0.92 0.97Foam: polyur. ½” 0.09 0.11 0.22 0.60 0.88 0.94Plaster: smooth on tile/brick 0.013 0.015 0.02 0.03 0.04 0.05Plaster: rough on lath 0.02 0.03 0.04 0.05 0.04 0.03Marble/Tile 0.01 0.01 0.01 0.01 0.02 0.02Sheetrock ½” 16” on center 0.29 0.10 0.05 0.04 0.07 0.09

Wood: 3/8” plywood panel 0.28 0.22 0.17 0.09 0.10 0.11Miscellaneous 125 Hz 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz

Door (solid wall panel) 0.1 0.07 0.05 0.04 0.04 0.04Glass (small pane) 0.04 0.04 0.03 0.03 0.02 0.02Chalkboard 0.01 0.01 0.01 0.01 0.02 0.02

Computation of Noise Reduction Coefficient (NRC) / Sound Absorption Average (SAA) at 250, 500, 1000, 2000 Hz

Parts NRC MaterialWall1 0.05+0.06+0.07+0.09

4=0.0675 Concrete block – painted

Wall2 0.22+0.17+0.09+0.104

=0.1450 Wood: 3/8” plywood panel

Floor1 0.01+0.15+0.02+0.024

=0.0500 concrete or tile

Floor2 0.11+0.10+0.07+0.064

=0.0850wood on joists

Ceiling1 0.03+0.04+0.05+0.044

=0.0400 Plaster: rough on lath

Ceiling2 0.22+0.17+0.09+0.104

=0.1450 Wood: 3/8” plywood panel

Chalkboard

0.01+0.01+0.01+0.024

=0.0125 Chalkboard

Window 0.04+0.01+0.01+0.024

=0.0200 Glass (small pane)

Cabinet 0.04+0.01+0.01+0.024

=0.0200 Glass (small pane)

Door 0.07+0.05+0.04+0.044

=0.0500 (solid wall panel)

Total Sound AbsorptionThe total sound absorption is computed by the product of each NRC and its corresponding

area and then computing the total value in Sabins.

Item NRC No. Area (in2) Area (ft2) SabinsFloor1concrete 0.0500 1 87542.35 607.933 30.397Floor2wood 0.0850 1 4482.00 31.125 2.646Ceiling1(plaster) 0.0400 1 25147.50 174.635 6.985Ceiling2(plaster) 0.0400 1 33456.15 232.334 9.293Ceiling3(plaster) 0.0400 1 22407.00 155.604 6.224Ceiling4(wood) 0.1450 2 8595.00 59.688 8.655

Wall rear side (concrete) 0.0675 1 21375.85 148.443 10.020Wall rear side (wood) 0.1450 1 1589.40 11.038 1.600Wall front view (concrete) 0.0675 1 13381.93 92.930 6.273Wall front view (wood) 0.1450 1 6645.98 46.153 6.692Wall left side (concrete) 0.0675 1 10563.30 73.356 4.952Wall right side (concrete) 0.0675 1 19387.63 134.636 9.088Wall right side (wood) 0.1450 1 9522.375 66.128 9.589Window1rear side 0.0200 1 3156.40 21.919 0.438Window2rear side 0.0200 1 1517.50 10.539 0.211Window3front side 0.0200 1 1957.00 13.590 0.272Window4right side 0.0200 2 3640.00 25.278 0.506Cabinet 0.0200 1 21986.70 152.685 3.054Door 0.0500 1 3619.35 25.134 1.257Chalkboard 0.0125 1 9273.60 64.400 0.805αt 118.957

Room Volume:V= l×w×hV= 310×308.2×105V= 10031910in3

V= 5805.503ft3

V= 5805.503 - cabinet and other sidesV= 5805.503 – 229.028 – 21.153 - 79.980 – 63.4375V= 5411.905ft3

Reverberant Time:

T= 0.05×V∝t

T= 0.05×5411.905

118.957T= 2.275seconds

Treatment

To reduce the reverberation time, we decided to use acoustic tiles for the ceiling, carpet to the floor and foam to the wall.

For Ceiling NRC=0.22+0.52+0.56+0.454

=0.4375 acoustic tiles

For Walls NRC=0.9+0.84+0.99+0.984

=0.9275 foam

Item NRC No. Area (in2) Area (ft2) SabinsFloor1concrete 0.0500 1 87542.35 607.933 30.397Floor2wood 0.0850 1 4482.00 31.125 2.646Ceiling1(acoustic tiles) 0.4375 1 25147.50 174.635 76.403Ceiling2(acoustic tiles) 0.4375 1 33456.15 232.334 101.646Ceiling3(acoustic tiles) 0.4375 1 22407.00 155.604 68.077Ceiling4(acoustic tiles) 0.4375 2 8595.00 59.688 26.1135Wall rear side (foam) 0.9275 1 21375.85 148.443 137.681Wall rear side (foam) 0.9275 1 1589.40 11.038 10.238Wall front view (foam) 0.9275 1 13381.93 92.930 86.193Wall front view (foam) 0.9275 1 6645.98 46.153 42.807Wall left side (foam) 0.9275 1 10563.30 73.356 68.038Wall right side (foam) 0.9275 1 19387.63 134.636 124.875Wall right side (foam) 0.9275 1 9522.375 66.128 61.334Window1rear side 0.0200 1 3156.40 21.919 0.438Window2rear side 0.0200 1 1517.50 10.539 0.211Window3front side 0.0200 1 1957.00 13.590 0.272Window4right side 0.0200 2 3640.00 25.278 0.506Cabinet 0.0200 1 21986.70 152.685 3.054Door 0.0500 1 3619.35 25.134 1.257Chalkboard 0.0125 1 9273.60 64.400 0.805αt 842.99

Reverberant Time After Treatment:

T= 0.05×V∝t

T= 0.05×5411.905

842.9915T= 0.321seconds

Computation of Noise Reduction (NR)

NR = 10 log∝2∝1

where:a2 = after treatmenta1 = before treatment

NR = 10 log842.9915118.957

NR = 8.504dbThis implies that the noise is reduce by 8.504 dB

Determination of Transmission loss of Composite Transmission Loss (CTL)/TL of Common Wall

Concrete:

TLwall = 46 dB

τ= 1

antilog4610

τwall = 25.12 µ

Wood:

TLdoor = 43 dB

τ= 1

antilog4310

τdoor = 50.1187 µ

Glass:TLwindow = 31 dB

τ= 1

antilog3110

τglass = 794.3282µ

CTL=10 logΣsΣτs

Wall rear side:

CTL=10 log148.443+11.038+21.919+10.539+25.134

148.443×25.12µ+11.038×50. 1187µ+21.919×794.3282 µ+10.539×794.3282µ+25.134×50.1187µ

CTL = 38.181 dB

Wall front view:

CTL=10 log92.930+46.153+13.590+64.400

92.930×25.12 µ+46.153×50.1187µ+13.590×794.3282µ+64.400×50.1187µ

CTL = 40.280 dB

Wall left side:

CTL=10 log73.356+152.685

73.356×25.12µ+152.685×794.3282µ

CTL = 32.638 dB

Wall right side:

CTL=10 log134.636+66.128+25.278×2

134.636×25.12µ+66.128×50.1187µ+25.278×2×794.3282µ

CTL = 37.318 dB

Sound Transmission Class (STC)

Determination of Noise Reduction of Common Wall

NR=TL+10 loga2S

Wall rear side

NR=38.181+10 log842.9915217.073

NR = 44.073 dB

Wall front view NR=40.280+10 log842.9915217.073

NR = 46.172 dB

Wall left side:

NR=32.638+10 log842.9915226.042

NR = 38.354 dB

Wall right side:

NR=37.318+10 log842.9915226.042

NR = 43.034 dB

Determination of sound intensity level (SIL) within the room if SIL outside the room is 75dB (SILT)

NR = SILT – SILR

SILR = SILT – NR

Wall rear side: SILR = 75dB – 44.073SILR = 30.927 dB

Wall front view: SILR = 75dB – 46.172SILR = 28.828 dB

Wall left side: SILR = 75dB – 38.354SILR = 36.646 dB

Wall right side: SILR = 75dB – 43.034SILR = 31.966 dB

Materials Used in Treatment

Acoustic Tiles

Acoustic Foam