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Lecture 27 - Engineer’s Cornpmgation Pad No 957 911E EFL...

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Unformatted text preview: Engineer’s Cornpmgation Pad, No. 957 911E EFL 437 .9 29/0 g #7 92/ Soar/ad iQo—WOQMCWM‘K‘ ak—vg—M Sanka? MP (cub SPFmLsR Lars-.4 54 ‘c % ////6t«él #45 Land q/ /'Sf_zn 1414/5 fora] (9‘61 film WW; ““7 J‘Fm’w sou/r4; too 735 tfiJ‘au/ru 404/.» {W W PA AkfiW. / )rééé ‘ 4 = 20 “J" (do h» W5» /00M ,9 6= 4048 /‘ W Jaw/4 IVA/#51? 5W1,“ /eo.;, W WT- POHJW 911/?L/(V0l‘t’A/L Swat/£14 %:-#.4'& = SH, @ (W W 5W LJT‘I'L. (lfvfpawa/ =- l \A/ “MA WWW IfmrcropLsM I). .ckj £79.5‘M51 ohm /¢W€(5F—MW 57r149m Why/Mia»: :flgé/z: ovgfifig L4,. ”0 5"“4’16 7’44qu Mfg, mi¢ M442” [22 WW Qua-7V“ yAz, To W64 Miccu/oé/QM: lhkmerl I) Pct/#59419“? 4 I,‘ Garmm m‘_chWJJ A2;0_[M 7 'llya/vouij £7 Z048 Z)M'edNCV-‘éam;/é M1;clr—¢')QL4OW Ww(w7 M spifflfj 2909476;me SPaMS We»? Wfim #14;me Dj J ) 7 >17 T*— MUM/6 4)P~,1L5f¢d<ers :fiw M7 draw— mrwaf W, awawéqm Maj/51W Mmca; M 14-? Nam» W! (firm/r Aw; «I f’MJA/W} (Sf-94W FMS! 717V? 6%?” 0(0pr SWSIKA/J'fi) ELL—LOW V‘“*% l” (OW/“é (W fimmrmfkehb 4 #:593-M: 6; ~ ~15???— /uJan,_L &\ \‘S louifimkzr-‘v ”47¢ JISW‘Q KM ‘3’“! SpeaKW 3M 1 Engimer'z Cornmx‘ta'itifin F NO. 3:77 711E ¢?4.4930 1010} __,_._w: #17 PM; W flm aéac‘xf fay/éédc m Ssm/ M4)»%VW 37;,é4f. fif/flMr‘mu/m MA¢VC Mia/a 17; MM Wén W M mad-4 ”4,2pr W am: /0/03,9 (#%7m mum-op W) gijL WJ—7fié’vflz [7 mM/ (47% qéfiq/f /0/6 7 WIMW from: 5% Mix/5%] % W7 ,2 2 '43 %féfl/~ 7Wé21%wnp¢m /9¢9f 54441 W wand/fl '— Ml/WAWW 7'54?) % J’oflz fiéufmvcfg; [7'6 lkcl—Wfl‘ PM: ‘ Q— C/oH \Lofl/éécz ( “x W WOV-Cf’q’h— I //;«J JAM... .———va\) ’WI mud» x‘Hm 05+M47J/ you/x W 44—13 W" 740 Haida 944’s 4?" M/m WWW ”14%” //L., 7’» haosf row ”A a mar—ma“; (”Low/Q 16 , 8 Arbitrary loudness units iminating noise and weather conditions. been designed specifically .ker is therefore usually an lent for a natural reflecting provided. 'ironment Indoors se the sound source, we nsmission of its output. We :me when we put the sound l position and observed the ‘bed by the “space” around ie opposite extreme and e that is completely reflec- ould put out sound energy, asorbed. If we continued to me long enough, we could 1 pressure that would be h power is quite small. It vey Fletcher in his book immunication that it would ing continuously for one iergy to heat a cup of tea.” 8 ft), a typical male talker )r 34 microwatts (uW) of emale talker generates V. From a shout at this hisper, the dB LP ranges 1 dynamic range of about : produced sound energy osure (dying out slowly), in the process. 2 essential parameters of a t does happen. First, an :rnal volume (V), usually Second, it has a total , measured in square feet alls, and two end walls). lividual surface areas has The average absorption 3, II II I n if yQDILkonl’i f’kh/rryr-A’a a?» meg Fr DWI The Acoustic Environment j Dy ' 125 “coefficient (a) for all the surfaces together is found 311,2 n are the individual absorption coefficients by of the individual boundary surface areas, S is the total boundary surface area in square feet. [I = slal +sza2 + +snan (5'15) . . — S The reflected energy is 1 — a. Table 5-4 gives typical absorption coefficients where, for common materials. These coefficients are used are the individual boundary surface areas in . to calculate the absorption of boundary surfaces 51,2,mn . . (walls, floors, ceilings, etc). square feet, Table 5-4. Sound Absorption Coefficients of General Building Materials and Furnishings Materials Coefficients 125 Hz 250 HZ 500 Hz 1 kHz 2 kHz 4 kHz Acoustical plaster. (“Zonolite”) ‘/2 in. thick trowel application 0.31 0.32 0.52 0.81 0.88 0.84 l in. thick trowel application 0.25 0.45 0.78 0.92 0.89 0.87 Acoustile, surface glazed and perforated structural clay tile, perforate ' surface backed with 4 in. glass fiber blanket ofl 1b/fl2 density 0'26 0'57 0'63 0'96 044 0‘56 Air (Sabins per 1000 ft” 2.3 . 7.2 Brick, unglazed 0.03 0.03 0.03 0.04 0.05 0.07 Brick, unglazed, painted 0.01 0.01 0.02 0.02 0.02 0.03 Carpet, heavy , on concrete 0.02 0.06 0.14 0.37 0.60 0.65 on 40 oz hairfelt or foam rubber with impermeable latex backing 0.08 0.24 0.57 0.69 0.71 0.73 on 40 oz hairfelt or foam rubber 40 oz hairfelt or fomn rubber 0.08 0.27 0.39 0.34 0.48 0.63 Concrete block coarse 0.3 6 0.44 0.31 0.29 0.39 0.25 painted 0.10 0.05 0.06 0.07 0.09 0.08 Fabrics light velour, 10 oz/ydz, hung straight in contact with wall 0.03 0.04 0.11 0.17 0.24 0.35 medium velour, 10 oz/yd2, draped to half area 0.07 0.31 0.49 0.75 0.70 0.60 heavy velour, 18 02/5 yd2 draped to half area 014 0.35 0.55 0.72 0.70 0.65 Fiberboards, ‘/2 in. normal sofi, mounted against solid backing unpainted 0.05 0.10 0.15 0.25 0.30 0.3 some painted 0.05 0.10 0.10 0.10 0.10 0.15 Fiberboards, 1/211’1. normal soft, mounted over 1 in. air space unpainted 0.30 0.15 0.10 some painted 0.30 0.15 0.10 Fiberglass insulation blankets AF 100, 1 in., mounting # 4 0.07 0.23 0.42 0.77 0.73 0.70 AFlOO, 2 in., mounting # 4 0.19 0.51 0.79 0.92 0.82 0.78 AF530, 1 in., mounting # 4 0.09 0.25 0.60 0.81 0.75 0.74 AF530, 2 in., mounting # 4 0.20 0.56 0.89 0.93 0.84 0.80 AF530, 4 in., mounting # 4 0.39 0.91 0.99 0.98 0.93 0.88 515:2?igia3g‘: in. unperforated cement asbestos board mounted over 0.18 0.11 0.09 0.07 0.03 0.03 Floors concrete or terrazzo 0.01 0.01 0.015 0.02 0.02 0.02 linoleum, asphalt, rubber, or cork tile on concrete 0.02 0.03 0.03 0.03 0.03 0.02 wood 0.15 0.11 0.10 0.07 0.06 0.07 .» 126 Chapter 5 a“ Table 5-4. (continued) Sound Absorption Coefficients of General Building Materials and Furnishings Materials Coefficients 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz wood parquet in asphalt on concrete 0.04 0.04 0.07 0.06 0.06 0.07 gfplacgucstggrl u3:12t in. X 13V; in., 2 1n. thick cellular glass tile mstalled 0_13 0.74 2.35 2.53 2.03 173 Glass large panes of heavy plate glass 0.18 0.06 0.04 0.03 0.02 0.02 ordinary window glass 0.35 0.25 0.18 0.12 0.07 0.04 Gypsum board, V2 in. nailed to 2 in. X 4 in., 16 in. o.c. 0.29 0.10 0.05 0.04 0.07 0.09 1 . 2 . . . gfgbgfgnpggg; e/rs 211;; lallb/Sfipaxrth bituminous roofing felt stuck to 0.90 0.45 0.25 015 0.10 0.10 Marble or glazed tile 0.01 0.01 0.01 0.01 0.02 0.02 Masonite, 1/2 in., mounted over 1 in. air space 0.12 0.28 0.19 0.18 0.19 0.15 Mineral or glass wool blanket, 1 in., 5-15 lb/ft2 density mounted against solid backing covered with open weave fabric 0.15 0.35 0.70 0.85 0.90 0.90 covered with 5% perforated hardboard 0.10 0.35 0.85 0.85 0.35 0.15 covered with 10% perforated or 20% slotted hardboard 0.15 0.30 0.75 0.85 0.75 0.40 Mineral or glass wool blanket, 2 in., 5-15 lb/ft2 density mounted over 1 in. air space covered with open weave fabric 0.35 0.70 0.90 0.90 0.95 0.90 covered with 10% perforated or 20% slotted hardboard 0.40 0.80 0.90 0.85 0.75 Openings stage, depending on furnishings 0.25—0.75 deep balcony, upholstered seats 0.50—1.00 grills, ventilating 0.15—0.50 Plaster, gypsum or lime smooth finish, on tile or brick 0.013 0.015 0.02 0.03 0.04 0.05 rough finish on lath 0.02 0.03 0.04 0.05 0.04 0.03 smooth finish on lath 0.02 0.02 0.03 0.04 0.04 0.03 Plywood panels 2 in., glued to 2’/z in. thick plaster wall on metal lath 0.05 0.05 0.02 ainfidrnggnptgrdepver 3 1n. air space, with 1 1n. glassfiber batts r1ght 0.60 (130 0‘1 0 0.09 0.09. 0.09 3/8 in. 0.28 0.22 0.17 0.09 0.10 0.11 Rockwool blanket, 2 in. thick batt (Semi-Thik) mounted against solid backing 0.34 0.52 0.94 0.83 0.81 0.69 , mounted over 1 in. air space 0.36 0.62 0.99 0.92 0.92 0.86 mounted over 2 in. air space 0.31 0.70 0.99 0.98 0.92 0.84 Rockwool blanket, 2 in. thick batt (Semi-Thik),covered with 3/15 in. thick perforated cement-asbestos board (Transite), 11% open area mounted against solid backing 0.23 0.53 0.99 0.91 0.62 0.84 mounted over 1 in. air space 0.39 0.77 0.99 0.83 0.58 0.50 mounted over 2 in. air space 0.39 0.67 0.99 0.92 0.58 0.48 Rockwall blanket, 4 in. thick batt (Full-Thik) mounted against solid backing 0.28 0.59 0.88 0.88 0.88 0.72 mounted over 1 in. air space 0.41 0.81 0.99 0.99 0.92 0.83 mounted over 2 in. air space 0.52 0.89 0.99 0.98 0.94 0.86 Rockwool blanket, 4 in. thick batt (Full-Thik), covered with 3/ns in. thick perforated cement-asbestos board (Transite), 11% open area mounted against solid backing 0.50 0.88 0.99 0,75 0.56 0.45 mounted over 1 in. air space 0.44 0.88 0.99 0.88 0.70 0.30 [ Table 54. (continued) I mounted over 2 in. air S] Roofing felt, bituminous, tw air space Spincoustic blanket 1 in., mounted against 5- 2 in., mounted against sr Spincoustic blanket, 2 in., Cf asbestos board (Transrte), 1. Sprayed “Limpet” asbestos 3/4 in., 1 coat, unpainted 1 in., 1 coat, unpainted 3%: in., 1 coat, unpainted Transite, 3As in. perforated, ( mounted against solid b mounted over 1 in. air 3 mounted over 2 in. air 53 mounted over 4 in. air s paper-backed board, mc Water surface, as in a swim: Wood paneling, 3A3 in. to '/z i space Table 5-5. Absorption ‘ Mat Audience, seated, dependin; of seats Seats heavily upholstered witl heavily upholstered witl lightly upholstered with wood veneer, no uphols Wood pews no cushions, per 18 in. 1 cushioned, per 18 in. let *Values given are in sabins Table 5-5 gives typi- rather than percentage per—unit figures or in un Finally, the room v time, RTGO. This is the take a steady-state s01 terminated, to attenu illustration, assume 1 characteristics: V= 500,000 113, The Acoustic Environment 127 r——________—_— Table 5-4. (continued) Sound Absorption Coefficients of General Building Materials and Furnishings x als and Furnishings x o - ents Materials Coefficrents 1 kHz 2 kHz 4 kHz 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz _\ /_—____—____________________ 0-06 0.06 0,07 mounted over 2 in. air space 0.62 0.89 0.99 0.92 0.70 0.58 ofin felt, bituminous, two layers, 0.8 lb/ftz, mounted over 10 in. 253 2'03 1‘73 £1: spadge 0.50 0.30 0.20 0.10 0.10 0.10 0_o3 002 0.02 spincoustic blanket _. 0.12 0 07 0 04 1 in., mounted against solid backing ' 0.13 0.38 0.79 0.92 0.83 0.76 ' 0.04 0.07 0:09 2 in., mounted against solid backing 0.45 0.77 0.99 0.99 0.91 0.73 spincoustic blanket, 2 in., covered with 3/is in. perforated cement— 0.25 0.80 0.99 0.93 0.72 0. 58 0.15 0.10 0.10 asbestos board (Transite), 11% open area 0.01 0.02 0.02 Sprayed “Limpet” asbestos 0.18 (“9 0.15 3A in., 1 coat, unpainted on solid backing 0.08 0.19 0.70 0.89 0.95 0.85 1 in., 1 coat, unpainted on solid backing 0.30 0.42 0.74 0.96 0.95 0.96 3A in., 1 coat, unpainted on metal lath 0.41 0.88 0.90 0.88 0.91 0.81 0-85 0.90 0.90 Transite, 3/us in. perforated, cement-asbestos board, 11% open area 0.85 0.35 0.15 mounted against solid backing 0.01 0.02 0.02 0.05 0.03 0.08 0.85 0.75 0.40 mounted over 1 in. air space 0.02 0.05 0.06 0.16 0.19 0.12 mounted over 2 in. air space 0.02 0.03 0.12 0.27 0.06 0.09 mounted over 4 in. air space 0.02 0.05 0.17 0.17 0.11 0.17 090 0'95 0‘90 paper-backed board, mounted over 4 in. air space 0.34 0.57 0.77 0.79 0.43 0.45 0’85 0‘75 Water surface, as in a swimming pool 0.008 0.008 0.013 0.015 0.02 0.025 i—0.75 :22: paneling, 3/2 in. to ‘/z in. thick, mounted over 2 in. to 4 in. air 0.30 0.25 0.20 0.17 0.15 0.10 I—1.00 i-0.50 Table 5-5. Absorption of Seats and Audience* 0.03 0.04 0.05 0.05 0.04 0.03 0.04 0.04 0.03 Materials 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz Audience, seated, depending on spacing and upholstery 2 5_4 0 3 5_5 0 4 0_5 5 4 5—6 5 5 0_7 0 4 5__/ 0 of seats . . . . . . . . . . , _ Seats 0-02 heavily upholstered with fabric 1.5—3.5 3.5—4.5 40-50 405.5 3.5—5.5 3.54.5 0.09 0,09 0.09 heavily upholstered with leather, plastic, etc. 2.5—3.5 3.0—4.5 3.0—4.0 2.0—4.0 1.5—4.0 1.0—3.0 1' h ‘ ' . . — . 0.09 0.10 0.11 ig tly upholstered With leather, plastic, etc 1 5 2 0 » wood veneer, no upholstery 0.15 0.20 0.25 0.30 0.50 0.50 W d 0.83 0.81 0.69 0° pew; 18 , 1 h 0 40 0.92 092 0.86 no cus ions, per . in. engt . cushioned, per 18 in. length 1.8—2.3 0.98 0.92 0.84 *Values given are in sabins per person or unit of seating 0.91 0.62 0.84 0.83 0.58 0.50 0.92 0.58 0.48 Table 5—5 gives typical absorption units in sabins S = 42,500 ft2, rather than percentage figures. Sabins are either in E1 = 0.128. per-unit figures or in units per length. 0.88 0.88 072 Finally, the room will possess a reverberation therefore the RT 60 is 099 092 0.83 time, RT 60. This is the time in seconds that it will 0.0 49V 0.98 0 94 0 8 6 take a steady-state sound, once its input power is RT60 = Sa i ‘ terminated, to attenuate 60 dB. For the sake of illustration, assume a room with the following = 4-5 3- 075 0.56 0.45 characteristics: _ 0 88 0 70 0 30 (See Chapter 7 Large Room Acoustics, for a more ' ' ' V= 500,000 ft3, detailed development of this subject.) ...
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