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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
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