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LIA24190 LEAD INDUSTRIES ASSOCIATION. INC. 2 9 1 MAOIION AVINUC NEW YOAK. N. Y. 10017 TACIAHOMl ~ AJtIA CODE lit OA AMH August 6, 1964 SUBJECT: Reprint on Lend for Kolae Control To the Meabers of the Lead Industries Association, Inc.: The enclosed reprint of an article on noiae control frcia Aaerlcan CHy vaa prepared by the LIA staff after discussions with the editors of that nagailne. It appeared in the June, 1964 issue and several dozen requests for additional information have been traced to it. Copies of this reprint have also been called to our list of architects, builders, and contractors (about 12,COO in all) and will be cade available through the "Lead Library" in the next issue of LEAD. Additional copies are available for your use. The first 25 are free and, in bulh, larger quantities nay be had at our coat of $3.00 per 100. BT:bd Enc. with L*+d 7 How to Stop Noise By BRUCE FADER Mgr., Technical Services Lead Industries Association, Inc. Distributed by Lead Industries Association, Inc. 292 Madison Avenue New York, N. Y. 10017 rtrpnnlrrf frtsm June 1964 issue of 1 tr. ft. L D IV . N 2011.01 LIA2A192 .y'V-***-V A weU, w<*fc k* r*4 bJ<fc- fea*rfl /J**e*J, dirM+t M lff f-- lf f of flM pvtJb W UtfM, ih nrfi Wt *+*d >wwwi l#M *oro( l imm lifkfwtifirf <Uder block Mr*#*. How to Stop Noise By BRUCE FADER Mgr'., Technical Services Lead Industries Association, Inc. Slop (or a moment and listen. What do you hear? U you arc rvd> inf at home, probably nothing more than the dishwasher or television. Dut if you are In your office. you probably hear street noise, two tele* phone conversations in nearby of fice*. typewriter* clacking away, and possibly even transformer* or hesvy machinery on some other floor. You may have been unconscious of the noise until you stopped * listen out these background noise* have been vying for vour att^*jon, in troducing error* in your work, and sand|Kipermg your nerves. In a recent at tide, Time maga zine quoted the Air Force** Dr. von Gierke on noise. "It Impair* both manual dexterity and accuracy.** Mechanic* working near howling jvtv for example, were Inclined to rush through thdr job, getting it done rather thin getting it right The same article cites a study by the Aetna Lie Insurance Co. When Aetna improved the acoustic situa tion in its own office* - typlm* arran w*nt dawn by JtS machine aparatec* mad# S2% (war miiiaka* aa.ptayea tvmavar drappad 47% a cibtanteaism da<ra*ad 37.3%. Noise need not be deafening to be a serious hindrance. Office* not'd ivlvphone* and typewriter* and In dustry depends on dynamite and diocl*. We make more noise than any previous generation In history and every new mechanical aid and technical advance adds to the noise load. However, we can control It Most popple know about mate rials that absorb noise. "Acoustic'* erthng tiles, carpeting, heavy drape* and oventufTed furniture soak up noise and reduce it by cutting dowc echoes. Oddly, though, very few people realize that there are other methods of noise control- and aome of them are much more effective than absorption In dealing with the most common noise problem*. One of the best noise control measures consists of the paths from the noise source to your car. To build a good noise block, or wall, make it limp and heavy rather than stiff and light For example, a sheet of lead foil only OCOS inches thick produce* the same effect as a sheet of *4-inch plywood, despite the fact that the lead is lighter than the plywood (about ty pound per  **wc*'-r* ywmwi i LIA24193 leaded vl*fl end glo flber applied centre! vafvae - -4 adjacent plpJef * .nvced noise h this pressure* rt^vtMc sietle* (rj abort 30 decibel* square foot v* more than i pound). The lead is lirnp while the wood U tuff and acts like a drumhead. One can also control noise by preventing the Vibration of the noise-making d'-vice from radiating through the air as sound. This method will never be applied to people'i larynx** nr their proxy counterpart*, radio*. Intercoms and TV sets, hut it can change the angTy cLickity-eUck of a typewriter into a polite plunkity-plunk. Alert prod* uct designers make use of noisedamping maferwU, such as lead plastics, to effect good acoustical manners for office machinery, ap pliances, automobiles and industrial equipment While it nuy be diffi cult to solve office or home noise prublems on the spot with damping compounds, they can often be used to reduce big noises produced in industrial operations, power plants, pumping stations and similar loca tions. Noise Problems No two noise problems arc ever quite alike. They range from noise levels so intense as to risk perman ent hearing lou, down to rooms so quiet that the noises of "silent* bearings can be tested. In each case presented here the limpness and weight of lead or flexible Icadcd- The Relation of Noise in Decibels to Commonly Heard Sounds Noise le-vol U Decibels Description or fxomple temerks 0 faintest possible sound the tower limit of ev6> billsy varies widely 20 40 SO 60 to 0 100 ameng people and varies with the pitch of the sound teoves In e feint breeio whiiper of four fe five feet quiet cenforence room typical busy ofhee feud redie er hWl Inside e typical re11rood cor subway platform with (rein this Is about the loudest pulling 1* noise which con be taler* ated eight heart a day without some risk of hearing demoge 110 full symphony erchestre ploying loud passage 120 -many noisy Industrie! operations 120 noise level et the romp when o jet olriiner takes ell 12S r^iso beginning te be painful many experts fool shot half e minute exposure may produce permanent hearing lose 160 near e jet olriiner et fvd throttle plastic sheetings have been the basis of the solution. One gas utility faced * siluatuo tjptcal of intense noise which cm* not be avoided. Municipal opera tions in water pumping, power gen eration and ether essential functlotvs present similar problems. Natural gas arrived at the utility** pressure-reduction station at 150 psi. This pressure had to be reduced to 15 psi for distribution. Although the demand for gas fluctuates greatly throughout the day, the utility maintains the same pressure in the mains at all time*. To do this they used a double V-port control valve fn the lines at the station. The internal parts of theae valves casually resemble a factory whistle. And while the flow of gas past the valves did not produce a whistle, it did result in a throaty roar somewhat like a mixture of subway trains and waterfall* Noise levels ranged between 110-130 deci bels and though there was no other way to handle the gas, nobody was happy. Treatment The accompanying drawing ihowl the successful treatment, now em ployed in dozens of these stations across the country. The utility's maintenance men first wrapped the pipes and valves In two-inch-lhkk blankets of glaxa fiber. Then they covered them with flexible sheets of leaded vinyL These weighed 0.81 pounds per square foot and were less than 1/18 of an Inch thick. They *apod all the seams and joints, taking particular care that no cracks were left in the covering. This re sulted In: 30-decibel reduction ta *Ue levels In the pressure reductloss teem. e The ability of werkere te com verse in the rnm something they could not d previously. e melntenenee end Inspection toe- LIA24194 N'-J "V* Had ! SchadvU end with** grvmWieg. frvfv>y averyon* vald rd ih* ri #r "o kwy" l**whsr*. Onl/ six man-day* of labor and a it oderate budget for materials produced this cH-nge. When the Franklin Institute In Philadelphia scheduled a research project to evaluate `silent'' bear ing even normal noises in the work area were excessive. These included street traffic, normal conversation and activity of half a d&rcn tech nicians and researchers, occasional machining or sheet-metal work, background noise of equipment on test and the usual ventilation and other noise sources. Requirements of this sort are not so uncommon In municipal operations either; of fices and meeting rooms where con fidential material U discussed, police interrogation rooms, study rooms and libraries should, ideally, offer the same degree of acoustical protection. The available workroom had con ventional drywalls (*i-mch plaster board on both sides of wood studs). Inside the mom technician* added wood furring strips and then nailed i/16-lnch sheet lead to the furring. They finished the inner wall with plywood, also on furring, to support Instruments, piping, etc, and acous tic tile. This rc*ti!tcd in an Improve ment of at least 14 oeclbcts and probably much more (the original wall was not tested and we based the Improvement on the best pos sible performance it might have given), ft took careful attention to other dctaiU, of course, to achieve this degree of Isolation. The ceiling and the door and other sound paths Into the room were treated and sealed, but the final result Was well worth the effort. As finished, the room, m-w 45 decibel* quieter than its surroundings, permitted the test* to be carried out on schedule. It costs very little compand to 7* 4 i -J---<a building a separate facility and the institute's stall did tne whole Job In leu than sis weeks from Jie first planning to the first actual bearing test. Seldom do budgets provide all the meeting rooms, special-purpose rooms and schoolrooms that local government would tike to have. Leaded vinyl plastic sheeting makes such rooms ava.laWc at Lille extra cost. A sheet of leaded plastic ' inch thick and weighing three pound per square foot is supported on s roller, motor driven and in stalled In the ceiling. Such a unit runs between the front and rear walls between two schoolrooms in a t^jng Island high school. In the unrolled position the vinyl forms a wall, with its own built-in rotl-up blackboards with a rating of 51 decibels. This equals or exceeds most lightweight cinderblock Walls. Classes held in the tw'o rooms do not Interfere with each other any more than they would in conven tional classrooms. However, to ac quire more space for special events the teacher unlocks the control snitch and rolls the wall into the ceiling. Obviously, one large meet ing room can be divided up by these walls to serve two, three or more group* without losing its use fulness as a Urge auditorium or calling for hours of expensive Ubor to make the changeover. Transformer Noise The hum of big power trans formers does more than annoy, it costs money. When focal resident* complain, utilities face alternative* such as altrraUons, rebuilding or replacement of the offending unit To udve the problem before il comes to this, one utility worked out a design for a transformer en closure that trims la to 2d drcibcU from the radiated noise. The en closure makes use of a laminate of steel and lead and has an interior facing of glass-fiber batting. Sheet lrad simplifies construction of this sort because it bends eatly to fit the strel supporting structure ex actly. Polygraph Room T7ie po!>grvph, or lie detector, bus proven its worth In speeding police Investigations by eliminating the innocent and c>*nfimung state ments. Out in oidrr to get un equivocal results with a polygraph the test must be kept free of sud den or stattiing noises and inicrrupUonv Since the polygraph U such a recent additi. j L> live equip ment of law enforcement it is aetnerirrr* allocated a rorm or space far from ideal. In the Bergen County Courdw_'i*c in Hackensack. N. the official* *et aside one of the regular rooms of tl- Lenten County Prosecutor's Office for polygraph examination*. The office walla were hollow-steel movable partitions and, to^eihe.* with a number of sound levies around doors and through the ventilating system, they provided only 24 decibels of noise reduction. It came to the point where a poly graph test had to be scheduled for after hours (hard to do in the typical situation) or it meant con ducting the normal work of the office on tip-loe and in whispers. Lsmin^ting 1/lfUinch lead to the waits and waling up the sound leaks produced a minimum noise reduction of 40 decibels. The ex am.:*--ti-in* no lunger require un usual measures to Insure excellent U-sling conditions. Although many other examples could be cited, the modern practice of soundproofing with lead is suQ quite young. Most contractor* and material supplier* are not yet familiar with it The materials and techniques used, however, are wide ly available and quite easy to under stand. Sheet lead can be painted as a finish surface and the leaded plastic Is available In colors and tcstsrv* and can even be had with permanent printed decorator design or a doth finish laminated to Jt Some of the other materials In clude prelaminatrd building stock of lead-gypsum hoard, lead plywood, lead-cored doors, leaded troweling and sealing compounds, and other specialties. Inf*.,-nation cn the status cf theas material*, the performance that they can be expected to give, and help in selecting and using them are all available through the Lead Indus tries Association, Inc- 292 Madison Ave., New York. N. Y. 10017.