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1947-48 Theatre Catalog, 6th Edition, Page 259 (245)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 259
Page 259

1947-48 Theatre Catalog, 6th Edition, Page 259

TABLE leAirborne noises originating outside the treatre and methods of their exclusion.

Ingress Method of Exclusion

Airtight fit. (This is requisite for eflicient operation of ventilation system also.) Doors opening on alleys or halls are often less of a problem than if they open on the street. Preferably 'open only into spaces which can be kept reasonably quiet.


Windows Do not belong in a theatre. Double where used and not capable of being


Exclude sound from loft by roof insulation, solid catwalks, tight doors.

Ceiling cuts

Projection Quiet machines. Sound

booth absorbent walls and ceiling in booth. Windows in viewing ports,

Ventilation 1. No metal connection

ducts between blower and steel

structural members.

2. Ducts large enough not to rattle or whistle when blower operates at full speed (above normal operating speed).

3. Sound insulated ducts.

Vibration from sump pumps, blowers, etc., hardly noticeable as noise in the air, becomes noise when structurally transmitted to the house.2 A concrete slab will usually transmit sound more efficiently than a brick wall.


1. List the sources of noise (this will include a noise survey of the site). (See Table 1, Table 2, and Table 3.)

2. List the means of transmission by which such noise might be conveyed to the house.

3. Provide in specifications for elimination of noise at the source wherever possible, for example, maximum allowable noise from machinery, vibration insulating mounts, and so forth.

4. Provide in design for minimum transmission of sound to the house: doors opening on alleys, roof insulation, no single door having direct access from outside to house or stage which must be used during performance, and so forth.

5. Provide in specifications for minimum sound transmission by materials in all places where sound exclusion is a factor: adequate minimum transmission factor by emergency exit doors, interior walls, and so forth.

The specification (5) is arrived at by subtracting the desired house sound level from the level of the maximum outside noise. (30 db. inside level, 90 db. outside level-minimum allowable attenuation by door in frame 60 db.)

Acoustic characteristics of most building materials are known and widely pub 2Auditorium exclusive of stance.


lished. Most suppliers of building materials will have sound transmission tests made of their products if they have not been made. Most contractors who install machinery will plan their installation with reference to a maximum noise specification and guarantee to meet such a specification.

Note: All specifications dealing with sound should include a statement of the frequency range to be covered. Acoustic measurements are conventionally made at octave intervals from 128 to 4096 cycles per second. A 60-cycle hum can be most annoying, as can a 10,000 cycle squeal. The ear responds to frequencies from 16 to 16,000 cycles per second, and a subway rumble is felt at even lower frequencies. For building material specifications and noise level calculations then, materials must often be tested for transmission of higher and lower frequencies than has been conventional practice.


Sight lines are apparent on blueprints. Anyone can take a ruler and see from the architects designs whether or not it will be possible for the audience to see the show, and presumably anyone who builds a theatre will make a reasonably thorough sight-line analysis of the designs before approving them. No matter how much faith he has in his architect, he seldom cares to overlook any chances of error when he has a large investment to protect.

Blueprints per se will not, on the other hand, show whether or not the audience will be able to hear. Much of the data from which acoustic analyses are made are to be found in specifications for wall and ceiling surfaces, equipment, etc. The apparatus and engineering data for finding out from plans and specifications whether the theatre is acoustically good or not are not ready to the hand of the layman.


Acoustic studies must be conducted coincidentally with the design if the design is to avoid the risk of considerable alteration, but this logical procedure is

TABLE 3-Solid-borne noises and methods of their prevention.

Source Method of Prevention

Snoring Put on a good show.

Train rumble Only satisfactory solu (subway, ele- tion is to float fioor and

vated, surface) ceiling supports and, in case of excessive vibration, interior walls, as in radio broadcast studio design.

Vibration from See above, or fioat the non-theatre fioor of the facility at functions of which the vibration orbuilding (gym- iginates.

nasium, bowls

ing alley)

Motors, Floating mounts. Machinery

Switches Use mercury switches. Plumbing More than one wall be tween house and facility. Isolate from structural members.

still lamentably far from common practice. The science of architectural acoustics is new. Architects, generally have not been trained in it; in fact where acoustics are concerned, a curious obtuseness often prevails.

Though this situation shows some signs of improving, most existing and new theatres suffer from one of the four common architectural approaches to the problem of making it possible for the audience to hear, each of them successful in getting a good theatre about once in a thousand tries.

The first is to trust to luck: after all, the Metropolitan Opera House was built on that plan. No one has hit the jackpot since, however,

The second is to use a rule of thumb; it varies with what rule and whose thumb, but a few people, with much experience in theatre building, have learned perforce a little about acoustic

TABLE ZeAirborne noises originating in the theatre and methods of their prevention.

Source )Ietllod of Prevention Heat the house entirely by circulated air, or wall or fioor radiation.

On stage, 1. Radiator return line graded to avoid condensate and resultant banging.

No valves to hiss.

2. Circulate hot water rather than steam.

Stage Wagons 1. Well made ball or rolDiscs ler bearing casters run(Noise magni- ning on level tracks infied because of stalled over stage floor. revereberant 2. Revolving stage on its stage floor) own support structure (quieter than disc on stage floor), 3. Elevators are quiet unless they are of the screw jack type and run too fast.


Dietllod of Prevention


Audience (Talk, 1. Make rear crossover shuffling) as sound absorbent as possible.

2. Lobby doors opposite aisles used for exit, not during show.

3. Divide rear crossover from house by a wall# a glass wall for motion

picture houses, (This

eliminates the standee


4. Carpet.

5. Silent seats. Orchestra pit Rubber feet on chair

legs and stands.

Locate only where one open door will not permit sound to reach house or stage. Light instead of bell on stage.

1947-48 Theatre Catalog, 6th Edition, Page 259