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B9006 1184 BB006 1200 SOUND CONTROL SERVICE ACOUSTONE SABINITE ACOUSTICAL PLASTER SYSTEM OF SOUND INSULATION SOUND INSULATIVE FLOORS, WALLS, CEILINGS SOUND INSULATIVE MACHINE BASE SOUND INSULATIVE DOOR s I 1 2 3 J4i; Dominion Gypsum Company, Ltd. 1221 BAY STREET Toronto, Ontario | G-J Copyright in Canada. 1931. By the Domlr on Gypsum Co.. Ltd. 3M-4-31 PRINT: O IN CANADA r\j o . j. k THE BLUE BOOK OF SOUND CONTROL SERVICE RESEARCH, DEVELOPMENT AND SERVICE Research and Development All D.G.C. Sound Control materials and Systems arc the esult of directed research in a modern building, especially quipped for that work. The research work is carried out under lie direction of trained physicists and chemists, architectural ngiqeers and investigators, comprising a personnel of some iftv individuals. Here new materials and methods are prolueed and tested and improvements developed. The fundamental nature of the laboratory's approach to my problem is well illustrated by the following: Some years igo they were asked to develop an acoustical absorbent of ;reat efficiency which as well would be incombustible, withstand ill the hazards of building construction and occupancy, equally idaptablc to new or existing structures, and one which would be decorative and appropriate to any architectural treatment-- Aeoustone is that product. The laboratory is unique in possessing the only complete sound chamber, owned and maintained by a manufacturer of acoustical products; a carefully calibrated aceoustical measuring stick to use during the development of acoustical products and as a guide to the scientists who are developing them. It is also used for control tests on the company's output, so that the acoustical absorption and sound insulation afforded by the sound control products of the Dominion Gypsum Company, Ltd., is constantly maintained equal or superior to the published determinations of recognized acoustical laboratories. Service The Dominion Gypsum Company, Ltd., acoustical engineers, arc completely equipped to assist architects on any problem involving sound absorption, acoustical correction or sound insulation. They render this service, without charge and without obligation, in advance of construction or will gladly advise corrective methods for existing buildings in which sound difficulties are experienced. In auditoria this service includes analysis of the elTect of curved or other sound concentrating surfaces, and investigation for objectionable echoes. In each case it indicates changes in design where they seem advisable. Where the reverberation is too great for comfort, recommendations are made for econ omically covering the necessary areas with acoustical absorbents. Because the Dominion Gypsum Company, Ltd., handles all phases of the problem and provides, not only materials for sound absorption, but also a complete system for the insulation of sound, architects are assured that absorption materials will not be recommended where sound insulation is required or vice versa. CONTENTS SOUND ABSORBENTS D.G.C. SYSTEM OF SOUND INSULATION Aeoustone, The D.G.C. Acoustical Tile Description, etc...................................................................Page 2 Specifications ...................................................................... Page 3 Sabinite Acoustical Plaster Description, etc...............................................................Page 3. I Specifications ...................................................................... Page 4 Where Acoustical Correction is Necessary..................Page 5 Definitions--Technical Data......................................Page 6, 7 Elements.................................................................................. Page S D.G.C. System in Fireproof Construction.... Page S, 0,10 D.G.C. Sound Insulative Machine Bases ............. Page 10 Thermofill for Sound Insulation................................. Page 11 D.G.C. Svstem for Non-fireproof Floor Construction I'age I I D.G.C. Sound Insulative Door................................. Page l I Fireproof Gypsum Roof, Floor and Partitions Page 12 ACOUSTONE--Actual Size Showing Texture and Enlargement Showing Porosity :i*wuiaa *., t PAGE i J3 J3 O o O' I(S o ACOUSTONE--D.G.C. ACOUSTICAL TILE Composition Acoustone is formed from filaments of specially processed stone. Its extremely fine, almost microscopic, porosity provides an unusually high degree of sound absorption. Incombustible Since it is made solely from specially processed stone fila ments, it is incombustible. Absorption The acoustical efficiency of Acoustone has been confirmed bv all the leading laboratories. The values below were obtained from tests by Dr. Paul E. Sabine at Riverbank Laboratories, Geneva, Illinois. Tile 1 " thick h" " 1" Pitch C3 Fitch C4 Pitch Co Pitch CO (250 d.v.; (512 d.v.) (1024 d.v.) (2048 d.v.) .16 .48 .00 .29 .62 .00 . 40 . 07 .00 . 52 . HO .04 Thickness Acoustone is made standard in 34 inch thickness. Light Weight Due to its extremely light weight, it is safely and perman ently cemented over plaster in both new and old work. Easily Cleaned The complete and thorough cleaning of the porous struc ture of Acoustone with an ordinary vacuum cleaner thoroughly evacuates any foreign matter that may become lodged in the tile. Accumulations of grease and dirt on the surface of the material are easily removed by the same method, or by using ordinary wall paper cleaner, restoring the original coior and appearance. The cost of such cleaning is much less than the cost of decorating an equal area of wall or ceiling: and the wear on the tile, incidental to the cleaning, is so negligible that no appreciable difference is made either in its appearance or sound absorbing ability after repeated cleanings over a period of years. Sizes Tiles are made in the following standard rectangular sizes: 0x6 in., 0x12 in., 12x12 in., OxlS in. Special shapes and sizes Durable Because Acoustone is made from especially processed stone, it does not deteriorate with age. may be obtained when required. Sanitary Outstanding Decorative Appearance Acoustone offers complete sanitation. It is inorganic, dura In additioii to its high degree of acoustical efficiency, it is outstanding in its decorative effect. The surface texture is quite similar to travertine stone, surpassing it, however, in the ble, completely cleanable. It provides an aseptic, readily and cheaply cleaned sound absorbent for hospitals, sanitoria and restaurants. richness and warmth it supplies through a wider range of color tones. From the viewpoint of design, it is adapted to har monious, unobtrusive inclusion in any decorative scheme. Installation and Guarantee Ashlar masonry walls for interiors can be constructed with Acoustone facings that arc as beautiful as natural stone. In teriors in the modern trend may be delightfully handled in tile The manufacture, installation and acoustical design of Acoustone is entirely under the control and is the sole respon sibility of the Dominion Gypsum Company, Ltd. with a metallic lustre in many shades and colors. The wide variety of shapes likewise adds flexibility--the de may be laid up in many '.:>n icstiug patterns. There is no di.-concertiug me chanical effect. Coloured bor ders, cornices in relief, and modified coffered work are easily obtained. Joints between tile units may be accented with a V profile or suppressed as de sired. Struck joints may be used with ashlar patterns. Colours Tiles are furiiislii" I in 'ulVctitii; white <r ovum. Spo ol.li colours wii! u1 made to or- dfi If for ;111v reason elian^cs in valour or rlTect arc desired, the tile surfaces may !>e brush or spray painted with auv of the brushing or spraying lac quers. Sprayed lacquers, con taining brmi/e oowders in sns- p. iimim* in' tin ippcar- unec <*i beii'E piaicd with the This policy enables the pur chaser to buy a result with out reference to the manner in which the result is obtained. It definitely fixes the responsi bility with the Dominion Gvpsum Company, Ltd., as it frees the purchaser or the architect from all details, engineering and installation. Such a policy, of course, means that tlie Dominion Gyp sum Company, Ltd. will refuse to install Acoustone where sat isfactory results will not be obtained. The company is prepared to make the installation of Acoustone in busy offices, banks, restaurants, brokers' offices, hospitals, etc., at times so that there will be no inter ruption in the usual routine. For this work only trained and experienced mechanics arc employed, who will carefully protect the walls, doors and furnishings against damage during the installation. metal used. hxhanMive tests have proven that painting with lacquer d(K' not reduce the acoustical efficiency or absorp tion of the tile. Oil paint, di luted with equal parts of thin ner. may be brush applied with out significant reduction in absorption. National Broadcasting Studio Ceilings and Walls of Act- . 'ie in varying shades. D G C. system of Sound Insulation used : >ughout for doors, walls and ceilings. Economical Acoustone is not expensive to install. It costs more than ordinary wall and ceiling decora ting, but by eliminating re decorating costs, over a period of years, the expense is less. CB 03 O o O' PAGE 2 tsj O UJ SPECIFICATIONS ACOUSTONE LONG FORM Note: XoUs are explanatory or advisory only and should not be included in the specifications. (1) Work Included Note: List and locate all sculls and ceilings to be covered with Acoustone. If more than one thickness of Tile is used, specify the thickness for the various areas. (2) Base Acoustone shall be applied direct to plaster or similar smooth surface. Note: On existing work Acoustone is applied over any firm, standard plaster finish. (3) Acoustical Treatment Material (3a) Acoustical treatment material shall be Acoustone in. thick and of colours selected by the architect. (3b) Joints between Tiles shall be (a V formed by accu rately beveling the tile edges) lux tietailed) (specify). (3c) Tiles on walls and lichls of ceilings shall be of size, shape, disposition and colour as shown on the various details and approved shop drawings. (4) Application of Acoustone (4a) Acoustone shall be completely erected by the Dominion Gypsum Company, Ltd., of sizes, colours and pattern shown on the drawings and details. (4b) The Tile shall be laid close, accurately cemented in position in full conformance with the manufacturer's specifica tions. SHORT FORM The contractor shall allow the sum of S.................... to cover the cost of acoustical treatment, using Acoustone to be fur nished and erected by the Dominion Gypsum Company, Ltd., as directed and approved by the architect. Installation in a Church Acoustone laid in AshUir pattern with struck joints matching in texture and random colour the native stone walls SABINITE ACOUSTICAL PLASTER Types Standard--Standard Sabinite is for use in locations not subject to moisture (high humidity). Number dS--Sabinite No. 3.3 is a special material for use in swimming pools, bath houses, hospitals, etc., specially devel oped to resist moisture. It has more absorption than the standard Sabinite. Absorption Tests expressed in percentages of sound absorbed made in 1030 at Riverbauk Laboratories lL)r. Paul If. Sabine), Geneva. Illinois. Sabinite type Standard No. 3S Hitch C3 Hitch C4 Hitch C5 Hitch CO (250 d.v.) 1312 d.v.) (1024 d.v.) (2048 d.v. .'JO .31 .3!) .33 .38 42 41 Composition Sabinite Acoustical Plaster is a permanent, reasonably priced, sound-absorbing plaster. Standard Sabinite is substi tuted, over the standard scratch and brown coats, for the usual hard, sound-repellent plaster finishes. Sabinite No. 38 is applied only over Special Exterior Stucco base coats. Sabinite absorbs sound because of its great multitude of tortuous, minute pas sages, which have their start in tiny openings at its surface. In these passages, inherent in the material, sound is repeatedly retlectcd, losing its energy to heat and friction. Thickness It is applied Jj-iu. thick in two successive coats, each Ja-in. thick, with the usual plasterer's tools. Appearance It presents the same appearance as a sand floated plaster finish. Colours Both Standard anil No. 3S Sabinite are furnished in white and four standard colours or tints: ecru, ivory, cream, bull. Special colours will be furnished on orders exceeding o tons. < hi small orders where special colours are required Sabinite uiav be integrally tinted on the job. ft can be painted or decorated after application without loss of eflicieuev. (See specifications.) Incombustible Composed of inorganic aggregates oonded together with gypsum plaster, long known as a fireproofing material, it is incombustible. Durable Sabinite Blaster is as rugged ami durable as the ordinary sand tloat finish. It is unaffected by dampness and does not shrink or swell with climatic changes. *'021 9 GOfcb PAGE 3 Sanitary Aeeause it contains no vegetable or animal matter, Sabinite is sanitary. I.ike any gypsum plaster it is vermin proof and the pores are too small to admit Hies or other insects. It may be disinfected or washed when necessary. Covering Capacity One ton of Standard Sabinite applied in two coats, each *4-in. thick, will cover a surface of from 70 to 75 sep yds. The average plasterer can apply 100 sq. yds. of Sabinite to full specifications in II hrs. To mix this material, including delivery to the mechanic, requires but 7 hrs. Sabinite No. 3S covers from 00 to 75 yards a ton, and requires 14 hours of a plasterer's time and S hours of mixing labor per 100 sq. yds. Application It is applied by the plastering contractor in lieu of the usual finish. Its installation is always supervised by an experi enced representative of the seller. Easy to Apply Nothing Init water is added to make Sabinite ready for application. It spreads with a trowel from the hawk, like ordinary plaster and bonds easily and lirmly to the base coat. Economical The low cost of the material, ease of application and ex cellent covering capacity, coupled with its relatively high sound absorption, makes Sabinite a most economical material. SPECIFICATIONS--SABINITE ACOUSTICAL PLASTER Note: Xthes are explanatory or advisory only and should not be included in the specifications. (1) Work Included Note: List and locate all mills and ceilings to be covered with Sabinite Acoustical Plaster. If both Standard and .Vo. 38 Sabinite are used, list and locate separately. IJ different colours of integrally tinted Sabinite are used, specify the colours for the various areas. (2) Grounds On walls, in addition to the usual grounds set for the scratch and brown coat plaster base, set additional Uj-in. thick grounds to assure proper thickness of the Sabinite and form nailing for wood trim, etc. All corner heads shall he set to conform to the increased plaster thickness. (3) Acoustical Treatment Material (3a) Acoustical Treatment material shall he [Standard) iand) ( Xo. dS) Sabinite Acoustical Piaster as manufactured by the Dominion Gypsum Company, Ltd. (3b) Sabinite shall he integrally tinted by the manufac turer at tlie mill. (3c) Sabinite shall be tinted as directed on the job by the inclusion of dry colour in amounts not to exceed 125 lbs. per ton of Sabinite. The usual precautions for handling col oured plaster shall be observed. Note: Literally tinted Sabinite should be a shade lighter than the same colour 'could be in paint because the texture of Sabinite ntsts a slight darkening shadow. pared material requiring no sand or other addition except water. It is applied in two coats in place of the regular scratch and brown coats. t4c) The scratch coat shall be thoroughly broomed before the second or brown coat is applied. The second or brown coat shall lie deeply raked after straightening. (5) Application of Sabinite The application of Sabinite shall only he made under the supervision of the Service Department of the Dominion Gypsum Company, Ltd., and after the plasterers have received full individual instructions. To the dry base coat, first apply one J^-in. coat of Sabinite mixed in accordance with the manufacturer's direction, adding water only to the material as supplied. The first coat shall be straightened with a darby and thoroughly broomed with a clean broom as soon as the water leaves the surface, the broom to be kept clean of all droppings and aggregate during the operation. The second coat shall be floated with a clean cork float to an even and porous surface when the water has left the surface. PAINTING SABINITE Spray Painting Sabinite may be spray painted. Depending on tin con ditions and the effects desired, the Dominion Gypsum Com pany, Ltd., will make definite recommendations as to the paint or spraying lacquer to he used and the type of spray ing equipment best adapted to the conditions. They will also furnish com plete specifications covering the application. 1.41 Scratch and Brown Coat Base Brush Painting i-4 i> Standard Sabinite-- All wails and o .lings '> re ceive Standard >.ibinit< dtall be given a scratch md imwu coat of gypsum | iusur con taining not more than two parts of sand by weight lo one part of plaster. \4b` Sabinite No. ds-- Hydraulic Sabinite shall only be ap; hod mer Special In terior stucco Base Coat Note: Special Exterior Xtin co Base Coat is a pre- Resraurant Installation Ceilings of Sabinite Aioustical- Plaster The only paint for brush application approved for use over Sabinite is one recom mended by the Dominion Gyp sum Company, Ltd., which may be tinted to any desired shade from the natural white bv adding color ground in oil. The Dominion Gypsum Company, Ltd., will furnish OS complete specifications covering u5 application adapted to the par o ticular conditions. o PAGE 4 rxj O Ul WHERE ACOUSTICAL CORRECTION IS NECESSARY uditoria The use of sourul absorbing materials on the walls or the clings of auditoria reduces the reverberation time to a proper el. so that hearing is made perfect at every scat location, rasideration should, of course, be given to designing the om so as to secure an ample and even distribution of sound, mcentration and dead spots, which result from improper fleeting walls or ceilings, will not be present if inclined and rved surfaces are properly handled. Gothic churches iuvariablv will require treatment, and even en will in many cases have dead spots in areas immediately ck of the transepts. In school auditoria and gymnasia, reverberation times ould be lower than those in churches and theatres. In talkingeture houses reverberation times should be still lower than in eatres if the sound of the projection apparatus is to be natural id without disconcerting barrel-like tones. Sound, like light, is reflected by the surfaces it strikes, ithough it is possible to design walls and ceilings and proseeum arches so as to obtain amply even distribution of sound; ifortuuatelv, many architectural forms, particularly domes and liptical curves, are apt to concentrate sound, producing areas greater volume in some parts of the room and consequent eas of low volume in other parts. No general rule can be given by which these difficulties are ' be avoided, but acoustical engineers can usually suggest slight tanges in the radii of curved surfaces and better angles for it surfaces which will provide a more even distribution of >und. Auditoria should be acoustically treated only after a ireful analysis. ment of the patient in cases of obscure neurasthenia and fatigue. The experiments on office conditions seem to indicate that in some instances a move to a quieter work-place may be as good as a rest, there being a difference of 19 per cent, in the energy expenditure increment following working in a noisy as compared with a quieter environment. Men and women seemed to be similarly affected, while the more skilled typists were adversely affected in output to a greater extent than were the mediocre typists." Hotels In hotels, elevator shafts as well as corridors are noise conveyors. Quiet guest rooms may he secured by treating the corridor ceilings with acoustical treatment. Many of the sounds occurring in guest rooms, and which seem to be transmitted through partitions, really eotne over the doors ami through the transoms from the halls. One has hut to remember his hotel experiences to know how annoying the clanging ot ele vator gates can lie when the hall transoms are open. Ceiling treatment, particularly in restaurants, lunch rooms and coffee shops, is recommended in hotels, as the clatter of dishes and the rattle of silverware is annoying to guests. It is also advisable to apply a sound absorbent on ceilings in kitchens and sculleries and main dining room for obvious reasons. The ballrooms and large meeting rooms of hotels used for conventions and other purposes are notoriously bad for speech. The use of sound absorbents on the ceiling usually suffices to correct such conditions. Hospitals fusiness Offices In the treatment of hospitals it is wise to apply acoustical absorbents to the ceiling, and in many eases to the side walls Acoustical treatment will reduce the noise level in an office om one-third to one-tenth. Everyone appreciates a quiet place i which to think. In an acoustically treated office the noise roduccd by jangling phone bells, strident buzzers, and paperlumping typewriters ceases to be a distraction. Tests have roved also that the quieting of offices makes for greater effiicncy. The acoustical treatment of office buildings and noisy ork-rooms pays for itself through the elimination of tnismlerstaudiugs, the reduction of errors, and the lessening of itiguc. Dr. Donald A. Laird, Director of the Psychological Labora- >ry of Colgate University, says, "Many executives think hat noise is inevitable, that nothing can be done to lessen and that any way it doc not matter. All three ideas are .'rong. Noise cuts into divi- of corridors. It is more necessary to do this than to apply the material in the wards and rooms themselves unless the hospital is located on a noisy street where sound absorbents on the ceilings will reduce the noise which would otherwise cause discomfort to the patients. The noises caused by the wheeling of trays of food, the clatter of dishes, and disturb ances in patients' rooms escape into the corridors and are carried into all of the rooms leading from the corridor. The introduction of acoustical treatment in the corridor will absorb this noise, making all the rooms leading from it quiet and rest ful. In hospitals it is quite common as well to treat ceilings and side walls of the labor and delivery rooms. It is excellent practice to apply treatment to the ceilings of all sculleries, kitchens and pantries which directly connect with portions of building used by patients. .etuls by lessening output and equiring more energy from Restaurants corkers. There is no evilenee that workers get used to loise. They may become imonseious of its presence, but lie effect upon their output Restaurants, quick lunelics ami cafeterias with their din of cluttering dishes and silver ware arc made as quiet as car peted dining rooms by treating emaius, the ceilings with high-efficiency "lu the Colgate University sound absorbents. uboralory, it was determined iv the use ol special apparatus Gymnasia and Natatoria hat noise ol usual office illicitity cuts into the output of proessioual typists on the average if .1 per cent. In higher mental vork, such as the executive lues, the cut into output is in lie neighbourhood of ill) per cut. "In a survey ol two large slants, it was found that abor turnover, absence from work and requests for transfer to other work were above the plant average in those departments which were noisy. "In many non-hospital cases the physician could apparently consider the working environ Installation in a Bank Paneled leilitie in various shades and sizes of Aeoustone Particularly where gym nasia and natatoria are built as integral parts of the building as is usually the ease iu schools and similar buildings, the ceil ings, at least, should be covered with sound absorbent material. In gymnasia besides tile ceiling the upper walls may well he included in the treatment. Many examples prove that where these rooms are pro perly treated the noises created within them are so successfully diminished that other depart ments in the building are un aware of their use. 9 0 2 1 9 0 0 fafl PAGE 5 DEFINITIONS--TECHNICAL DATA Note: The nomenclature of the science of acoustics is so relatively new and so possible of misapplication that to assist in clarity and understanding of analysis reports submitted by acoustical engineers, it seems advisable to define the more important terms and explain certain phases of the technical data. Data on Sound Control Those interested in the complete details of the subject should refer to Professor Sabine's Collected Papers on Acous tics published by the Harvard University Press. The Dominion Gypsum Company, Ltd., will furnish on request a publication containing interesting data on the theory of acoustical control, the formulas used, their application and the criteria of excellence for auditorium acoustics. This booklet also contains an extended discussion of the theory and practice of office quieting through use of acoustical absorbents. Sound Sound is a wave motion of the air or other elastic medium, capable of producing the sensation of hearing. This wave motion is set up by the vibration of a sounding body, and con sists of the successive vibrations of the particles of the medium. This vibration of the individual particles produces alternate rarefactions and condensations of the air or other medium at any point of the wave train. Speed of Sound Sound in air travels with a speed of about 1129 ft. per second at 68 F. Its velocity increases about 1.1 ft. per second for every degree rise of temperature. Intensity of Sound Intensity of sound may be defined as the sound energy per unit volume of the air through which the sound is traveling. Loudness Loudness is the degree of sensation produced on the ear corresponding to the intensity of the sound. Loudness in creases with intensity, but the difference in loudness between two tones of the same pitch is roughly proportional to the logarithms of their intensities. Hence an increase of as much as 25 per cent, in the intensity of a tone produces a barely perceptible increase in loudness. Resonance Resonance is the enhanced response of the total volume of air included in a room to a musical tone whose pitch coin cides with the natural frequency of vibration of that particular volume of air. It is frequently observed in small empty rooms and simply results in an unusual reinforce ment of particular low tones in comparison with other tones. It is sometimes a source of annoyance to a speaker upon an enclosed stage, and is undesirable in rooms intended for radio broadcasting or for phonograph recording. Rarely found in large or furnished rooms, it is seldom an important factor in auditorium acoustics. Interference Interference is a localized phenomenon which may be observed under proper conditions at any point in any room. In the simplest case, it results when sound of definite pitch from a single source reaches a given point by two paths of different length. Where this difference of path length is an odd number of half wave lengths of the sound, a condensation arriving by one path coincides with a rarefaction arriving by the other path; the two components of the resultant sound mutually annul each other. Obviously, there will be other points close at hand where the path difference is an even number of half wave lengths, when the two components will mutually reinforce each other. BB0Q6 120 Yorkminster Baptist Church, Toronto, Ont. George, Moorkouse and King, Architects Sabinite Acoustical Plaster. PAGE 6 Interference thus results in an uneven space distribution of Frequency sound intensity for a given pitch, and a marked variation at any given point in the intensities of sounds of different pitches. It The frequency of a sound is its number of double vibra tions (complete vibrations) per second. The frequency most becomes a serious defect when the focussing action of extended concave reflecting surfaces exaggerates the normal inequality that exists in every room. Spherical domes and cylindrical vaulted ceilings with centers or axes of curvature that fall close to the audience or to the speaker are fruitful sources of often used in acoustical calculations is 512, or one octave above middle C (C4). The actual frequency range which is of im portance in acoustical work extends from about 12S to 4096 D.V. per second, or about five octaves. delects of this type. Such defects can be avoided by proper design. They can be alleviated by the use of sound absorbent materials on the concave surfaces which produce them. Prevention is better than cure, and the designer who pro poses to use extended curved forms in an audience room should be competently advised as to the acoustical results to be Pitch Pitch is measured by the frequency of the vibrations. Middle C (.C3) on the piano has a period of 256 complete or double vibrations per second. The various octaves above middle C and those customarily considered in acoustical cor expected. Extraneous Noise Frequently, hearing difficulties resulting from disturb ing noise are ascribed to faulty acoustics. Noise of ventilating tans transmitted along air ducts are delivered to audience rooms, air conditioning machinery improperly mounted, thus setting up vibrations which are structurally transmitted, and finally street noises, may seriously lessen the intelligibility of speech rection have the following periods of vibration: C4--512 d.v.; Co--1024 d.v.; C6--2048 d.v. Some ears are able to hear vibrations as low as 14 or 16 per second and have an upper range limit that varies even more in separate individuals to almost 20.000 vibrations per second. The average ear can hear as shrill a sound as 16,000 vibrations per second. C4 is that used as the fundamental note in auditorium analysis. Careful investigation has determined that the pitch of office machines varies between Co and C6. in rooms that are otherwise satisfactory. Facts Concerning Absorption Percentages Echo Echo is the distinct repetition of a single short, sharp sound, due to direct reflection of sound from one or more reflecting surfaces. Like interference, echo is a localized de fect. It is seldom present as a source of acoustical difficulty except in rooms of large proprotions. Extended, unbroken rear walls frequently produce direct reflections annoying to the speaker, but unheard by the audience. Echoes from lofty ceilings, particularly when these are curved so as to produce marked concentration of the reflected sound, frequently re sult in poorer hearing conditions in scats near the speaker than in seats farther away. Multiple echoes resulting from repeated reflections may be observed under special conditions in very large rooms. Every auditorium design should be carefully investigated for echoes which would cause annoyance. Reverberation--Overlapping Sounds Reverberation may lie called "the persistence of sound in a room after it has ceased at its source.'' Professor Wallace C. Sabine said, "Sound bcingenergy, once produced in a coil- lined space, wil) continue until it is either transmitted by the boundary walls, or is trans formed into some other kind of energy, generally heat." When the interior surfaces of a room are constructed of materials which are highly retleetive. sound waves striking them bounce rapidly from Architects should know that laboratories in determining the co-efficients of absorption of materials submitted for analysis do not all use the same yardstick. For example, we find the same sample of material which tested 62 per cent, at C4 at the Riverbank Laboratories, testing 65 per cent, at another widely known laboratory. In order to equitably compare various acoustical products, the archtect should compare figures of the same observer. It would seem logical that the co-efficients used for com parison be furnished by laboratories using the identical methods that were employed by Professor Wallace C. Sabine in dis covering the absorption of various building materials, carpets, drapes, and persons, co-efficients which are recognized as standard and used by all laboratories in determining reverb eration times. The Dominion Gypsum Company, Ltd. uses the co-efficients provided by the Riverbank Laboratories, Geneva, Illinois, which were designed by Professor Sabine and had its sound chamber calibrated with his original pipes and by his so-called "four-orgau-pipc experiment." Too much stress should not lie laid on the rela tive co-efficients of absorption, particularly when the problem is that of quieting. In an office 30 x 50 ft., with a 12-foot ceiling, a difference of ter. points in the ab sorption co-efficient of the absorbent used produces less than a decibel (the least audible dilferenee iu loudness the human ear can detect) of difference iu the noise level. surface to surface, making many circuits of the room in every direction. The room is then Idled with sound which continues uutilall of its origi nal energy is dissipated. To illustrate; if the re duction iu noise level caused by a lib per cent, absorbent in this r - an is 5 I decibels, a TO per cent, absorbent pro duces a reduction of 5.6 It is easy to appreciate the resultant confusion due to the overlapping of .successive syl lables or notes in an audience room. Tile first syllable persists while tile next is uttered. Each syllable and note has to com pete with preceding sounds for tile attention of the audi ence. This eflect is throughout the room. It makes audition uncomfortable, difficult, or impossible, depending solely on the length of time a sound decibels. Such a difference is undistinguisiiablc hv the ear. yet tile difference in price of tlie material will frequently be as much as 10 or 15 cents per square foot. In this connection, the archi tect is reminded that the use of a low co-efficient absorb ent over a wider area is generally more desirable than the use of a high co-efficient material on a concentrated persists. The time a given sound of known intensity and pitch persists is the reverbera tion time of that particular room. London Life Insurance Co. , Ltd., London. Ontario .\nuiid hisulaltvt; Mat kin? Bust's area. It is the exception in auditoria where an absorbent of maximum co-efficient is required. 8021 90068 PAGE T Sound Insulation vs. Sound Absorption * Tlx: architect should differentiate between sound insula tion and sound absorption. The former has to do with prevent ing the passage of sound through walls, floors, ceilings, and other structural parts of the building. Sound absorption, on the other hand, has to do with the control of sound within a room, either reducing reverberation so that speech and music are properly heard, or reducing the noise level in the room to a mini mum. Although sound-absorbing materials will in some measure reduce the amount of sound transmitted through walls and floors, their value as sound insulators does not warrant their expense. Another point which often causes confusion of mind is that the intensity of sound as measured by physical standards does not represent the loudness of the sensation that reaches the senses. Loudness--the aural sensation of intensity-- is roughly proportional to the logarithm of the physical intensity. As well, no means are known of separating the amount of sound that passes through a sound absorbent and that which is actually absorbed (killed) by it; but even if 50 per cent, of the sound were compltetely annihilated, the remaining 50 per cent, would usually be sufficiently intense to permit of ordinary conversation being heard through walls. In order to stop effectively the passage of objectionable sound through walls, floors and ceilings sound insulation must be much more effective than this. This insulation the qualified acoustical engineer can pro vide. It can be done in existing buildings, although it is best done during construction. Moreover, for the reason that conveyor flights, vent ducts, piping, etc., carry sound and must be insulated, sound insulation should be the work of one con tractor who can be made responsible for the result. D.G.C. SYSTEM OF SOUND INSULATION ELEMENTS fl) D.G.C. System of Sound Insulation for Walls, Floors and Ceilings. (2) D.G.C. Sound Insulative Machine Bases for isolating vibration and noise in Machine Equipment. (3) D.G.C. System of Sound Insulation for Non-tireproof Construction. (4) Thermofill for Pipe Chases, Shafts, etc. (5) D.G.C. Sound Insulative Door. Floors in FLOOR, WALL AND CEILING CONSTRUCTION Purpose Uses To prevent the passage of sound from one room to another. It should be used wherever a high degree of sound insulation Theory and Description is required in either new or existiug buildings. Sound passes through a wall, floor or ceiling by vibrating it as Apartments, hotels, hospitals, schools, radio and talking a diaphragm. In the case of a wall, the sound strikes it and picture studios, music studios, club buildings, theatres, bowling sets it into vibration. The vibrating wall sets up new sound alleys, office buildings, etc., all require sound insulation treat waves, reduced in intensity on ment to a varying extent. the opposite side. The D.G.C. System of Sound Insulation is built upon the principle of pro viding a wall in which one side can vibrate while the other side Detail Section of D.G.C. Sound Insulative Floor, Wall and Suspended Ceiling Construction Items Furnished and Installed in the D.G.C. System of does not. This is accomplished Sound Insulation (See by constructing a furred surface supported on springs. These detail, page 9) springs act as "snubbers" in Ceilings -- Resilient Ceil reducing the amount of vibra ing Saddles. I.1 bin. Channel tion of the surface, and because Runners, Furring Runners, of their resiliency, prevent the Kocklath, Thcrmofill. remaining vibration from pas sing through to the opposite side. Note: We do not indude plaster or hanger rods. Advantages The D.G.C. System of Sound Insulation possesses the following advantages over other methods of sound insulation. (1) Permanence -- The efficiency of this construction, being primarily obtained by steel spring devices, is main Hanger rods should be furnished by others. 2 by 4ft. centers with first hanger 0 in. from all walls. Walls -- Resilient Wall Clips, Furring Runners, Rocklath, Cornerite. Note: We do not include tile walls or plaster. tained permanently. Floors--Resilient Sleeper (2) Fireproofness Chairs with tie wire and grout. incombustible material Wood Sleepers. Thermofill. and gypsum, are employed. Paper Membrane. (.3) Economy -- Because of its simplicity of construc tion, the D.G.C. System of Sound Insulation oilers a maxi mum of efficiency at a reason Space Required by the D.G.C. System of Sound Insulation. able cost. Note: We do not include Sale and Installation The D.G.C. System of Sound Insulation in Fir- proof Construction is sold and in stalled only by the Dominion Gypsum Company, Ltd., which assures undivided responsibility the rough and finished floor ing. Ceiling--Not less than t> in. to the bottom of Rocklath. Walls--2H in. from the face of tile wall to outside face of Rocklath. for the results. All work is Floor--in. from the installed by trained mechanics top of the floor slab to the under strict supervision. top of the wood sleepers. PAGE 8 " 8006 1209 DETAILS OF THE D.G.C. SYSTEM OF SOUND INSULATION PAGE 9 OIZT 90088 ' SPECIFICATION (SHORT FORM) D.G.C. SYSTEM OF SOUND INSULATION FOR FLOORS, WALLS AND CEILINGS Note: Notes are explanatory or advisory only and should not be included in the specifications. Note: This specification should be included under a separate heading of "Sound Insulation." (1) Work Included Note: Here list and locale clearly the walls, floors and ceilings to be treated. Also indicate the ollowing areas clearly on the plans'. Partitions--Indicate by heavy black line on the side to be insulated. Floors and Ceilings--Indicate on room schedules and by notations on floor plans and sections. (2) Sound Insulation The sound insulation as above listed and shown on plans shall be the D.G.C. System of Sound Insulation furnished and installed by the Dominion Gypsum Company, Ltd., Toronto, Ont. D.G.C. SOUND INSULATIVE MACHINE BASES Purpose To prevent the transmission of noise and vibration of motors and machines in buildings. Description The Dominion Gypsum Company, Ltd., Sound Insulative Machine Base has been especially designed for use under machinery of all kinds to localize vibration and the resultant noise. Its construction is essentially that of a rigid platform supported on very sensitive steel springs as is shown in the accompanying illustrations. These resilient springs "absorb" the noise and vibration of the machine so that practically none enters the floor upon which the machine rests. The platform has no continuous connection of any kind with the floor except through the resilient springs. The action of the springs in the base might be likened to those in an automobile, where the vibration and shock on the wheels is absorbed instead of being transmitted to the body of the car. Uses The bases are for use under fans, motors, pumps, elevator motor generators and control panels, oil burners, printing presses or any piece of equipment that is a source of vibration or noise. Advantages The D.G.C. Sound Insulative Machine Base possesses the following advantages: (1) Adaptability--Each base is especially designed and built for the piece of equipment that it is to support. The number of springs is determined by the load and characteristics of the machine. The standard base is of all steel construction with either a concrete or a steel plate top although it may be furnished with a platform of wood planking with maple floor finish. Special bases with cast top can also be furnished. (2) Economy--By the use of this base, equipment can be placed in that part of the building most desirable from the standpoint of efficiency and economy, without regard as to possibility of disturbances to adjacent parts of building. (3) Installation--While it will usually be found more economical to pour the concrete top at the time of erection, the base can be shipped complete with the top, and with anchor bolts imbedded therein. The wood top base can be provided with properly placed holes for bolting down the machine. The outline of the machine is clearly indicated, making instal lation very simple. If desired, we will furnish and install the base. The connecting of pipes, wires, ducts, etc., should be done by the proper trades. Connections should be made with a flexible coupling. SPECIFICATION (SHORT FORM) Note: List under heading of "Sound Insulation." L'nder all (name and describe items of equipment to be in sulated) the (specify which) contractor shall install D.G.C. Sound Insulative Machine Bases as designed and manufactured by the Dominion Gypsum Company, Ltd. r.' i . " r--_, ` * - * v*,.&.- I ! D G.C. RESILIENT STEEL CHAIR N-----THERMOFILL Section of D.G.C. Sound Insulative Base ^0 0 6 12, , Printing Press Installation Control Panel Installation PAGE 10 Fan and Motor Installation THERMOFILL FOR PIPE CHASES, ETC. Purpose--To prevent pipes from carrying sound, the hases should be filled with Thermofill and the pipes kept ree from all floor slabs and partitions in so far as possible. Thermofill is a dry, flocculent material of light weight, which acts as an effective sound deadener. It is easily installed and is low in cost. D.G.C. SYSTEM OF SOUND INSULATION FOR FLOORS IN NON-FIREPROOF CONSTRUCTION description The D.G.C. System of Sound Insulation is also adapted to :se on floors in wood joist construction. It is designed to urnish a high degree of sound insulation in non-fireproof buildigs at a nominal cost. Its use is particularly desirable in partment buildings of this type of construction, because of he ease with which sounds travel from one apartment to an other resulting in considerable annoyance to the tenants. Items Furnished by the D.G.C. Co. Resilient Sleeper Chair, Thermofill, Sleepers, Paper Mem brane. This construction will require 2J4 in - from the top of the rough floor to the top of the wood sleepers. Note: We do not include the sub or finished flooring. D.G.C. SOUND INSULATIVE DOOR description The Dominion Gypsum Company Sound Insulative Door mploys the same principle used in the Dominion Gypsum Company System of Sound Insulation. The two sides of the door are supported on resilient spring levices, which allow either side of the door to vibrate under he action of sound without the vibrations passing through to he other side. Advantages (1) Fire Retarding--Sheets of steel and asbestos on the nside of the door make it resistive to fire. (2) Light in Weight--The door, because of its construcion, weighs but slightly more than standard 1%-in. flush >anel doors of the same size. (3) Regular Hardware--No special hardware is required with these doors. The ordinary standard knob and lock set >perates with this door the same as with a regular door. The mdcsirability of special lever handle hardware is generally ecognizcd and a sound insulative door which operates with standard hardware fills a long felt want. (4) Effectiveness--The door is built upon the scientific principle of preventing the diaphragmatic vibrations of one side of the door from being transmitted to the opposite side. Its sound insulative efficiency is, therefore, remarkably high. (5) Economy--This door, although it possesses unusual advantages in a "soundproof" door, actually costs less than "clumsy" and less efficient doors used in the past. It is priced to permit its widespread use in hotels and apartment houses. Materials and Design The doors are furnished standard 2^-in. thick, in birch, unfinished, in either flush or panelled construction. Other wood veneers or any special design of panels can be furnished at slight additional cost. Special Items Furnished Special stops with rubber gaskets and threshold are fur nished with the door. Since no special jambs, trim or hardware are required, none are included. ZT2T 90088 Section of Door Showing Flush and Panel Construction PAGE 11 FIREPROOF GYPSUM ROOF, FLOOR AND PARTITION CONSTRUCTION The Dominion Gypsum Company also manufactures, sells and installs the following Fireproof Gypsum Products: Pyrobar Gypsum Roof Tile, both Short Span and Long Span. Sheetrock -- Pyrofill Poured Gypsum Roof Construction. Marks T System of poured Gypsum Roof Construction Pyrofill Monolithic Poured Gypsum Roof and Floor Construction. Pyrobar Gypsum Floor and Ceiling Tile. Pyrobar Gypsum Partition Tile. Pyrobar Gypsum Column, Beam and Girder Fireproofing, Full information will be found in our Red Book of Fireproof Gypsum Roof, Floor and Partition Construction, copy of which is available on request. DOMINION GYPSUM COMPANY, LIMITED 1221 BAY STREET - TORONTO, ONTARIO PAGE 12