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Publication numberUS2424634 A
Publication typeGrant
Publication dateJul 29, 1947
Filing dateMay 19, 1944
Priority dateMay 19, 1944
Publication numberUS 2424634 A, US 2424634A, US-A-2424634, US2424634 A, US2424634A
InventorsFrank Rieber
Original AssigneeInterval Instr Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Theater amplifying and sound distribution system
US 2424634 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)


Patented July 29, 1947 THEATER AMIPLIFYING AND SOUND DISTRIBUTION SYSTEM Frank Richer, New York, N. Y, assignor to Interval Instruments, Inc., New York, N. Y., a corporation of New York Application May 19, 1944, Serial No. 536,412

This invention relates to a theatre amplifying system, more particularly to a system for amplifying the various sounds given 01f from a stage and recombining them to produce harmonious results, and then reproducing them within the amphitheatre harmoniously with each other and with the sounds arriving at that point in the intensity of sound so high as to be disagreeable or even painful, whereas those in the last rows or in the back of the theatre may not receive sufficient intensity of sound for good reception.

Moreover, sounds of diiferent frequencies, that is, of diiferent pitch, are not transmitted equally well through the air, with the result that if the proper quality of sound is emitted from the loud speaker, the quality received by the distant portions of the audience may be notably deficient in the higher frequencies.

Moreover, if sufiicient sound is produced at or near the screen or stage to reach all portions of the auditorium, many neighboring residents may be unduly annoyed by the volume of the sound reaching them.

To overcome these difliculties, attempts have been made to utilize a number of loud speakers distributed through the audience, which may be placed apart by a very considerable distance. Under such conditions interference zones or sound shadows exist wherever the sound arriving from one loud speaker, at a given pitch, is in phase opposition to a substantially equal sound from another. Other corresponding zones exist where the sound coming from two different loud speakers reinforce each other at a given pitch and exaggerate that sound far above its. proper level.

It is a further object to provide a system including a number of microphones so arranged and controlled that the total reception will very closely resemble in its harmonious effects a sound reception at a single fixed point of reference Within the auditorium, thus reinforcing the sounds given oil at distant portions of the stage and bringing a proper balance throughout the whole scale range, and for all of the various instruments.

It is a further object to provide a system of sound reproduction which will produce through- 3 Claims. (01. 179-1) out the amphitheatre, even at a point remote from the stage, the same harmonious effect that is produced by the air-borne sound coming from a common point but reinforced by amplified sound.

It is thus an object of this invention to provide a reproducing system for a theatre which will to the maximum extent transmit to the audience in reinforced form the same artistic blending of sounds which would be heard in the most desirable portions of the amphitheatre.

The invention accordingly comprises a device possessing the features, properties and the relation of elements which will be exemplified in the article hereinafter described and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawing, in which:

The figure illustrates the amphitheatre with the apparatus installed therein in accordance with this invention In the drawing, the numeral l0 designates the stage of an amphitheatre on which there may be presented, for example, an orchestra. Distributed about the stage are a plurality of microphones arranged in concentric arcs. As shown, there are three such groups of microphones designated respectively as l I, I2 and i3, these arcs all being concentric about a reference point M which, as shown, is in the amphitheatre in front of the center of the stage. The wires l5 and I 6 connect all the microphones H together to an acoustic reservoir 20. Similarly, the wires 2| and 22 connect all the microphones l2 to an acoustic reservoir 24, and all the microphones in the next circle comprising, in this instance, only one connected by wires 25 and 26 with an acoustic reservoir 21.

; In my vcopending application filed of even date herewith and bearing Serial No. 536,407, I disclosed an acoustic reservoir eminently suited for use in this invention, said reservoir comprising primarily a disc on the periphery of which is helically wound amagnetic wire and mounted about theperiphery of the disc are three magnets, one for making a magnetic record on the wire, one for reproducing sound from that magnetic record, and one for wiping off the magnetic record. This disc is driven at a constant speed. The angle between the reproducing magnet and the recording magnet may be varied at will in order to vary the timing of the reproduction. The

similarly the sound coming from the location of k the microphones II will lag still further behind.

This error increases with the size of the orchestra;

where necessarily the players are placed atg-reater distances from each other. To correct these dif V ficulties in reception, the acoustic reservoir 24 is arranged to delay the reception of the input from the microphones l2 long enough to bring it into phase with the reception from the microphones I H. the reception coming from the microphone T 3 to bring it into phase with that coming from the microphones H. In accordance with these inventions, these three reproduced records with their properly correlated timed delays are now united for reproduction.

It will be noted, however, that this delay of reception from the microphone 13 until the sound from the microphones II has caught up with it, is :acorrection in the right direction to bring that sound into synchronism with the air-borne-sound, at the point A. v I

By an arrangement following the same principle, the reproducing loud speakers are similarly harmonized. As shown in the diagram, each of the variables coming from these microphones respectively is passed through an amplifier Z8, 29 or 3B, and the output of these amplifiers is car ried through a mixing amplifier 3|, the secondary 32- 33 of which could 'be fed to a loud speaker which at any given point in the amphitheatre would give a harmonious reproduction of all of the sound coming from the orchestna with the harmonious sounds emphasized, and those which were not harmonious becauseof being improperly delayed, blanketed out. For the purpose of introducing this sound to the audience, however, there is arrangedwithin the amphitheatre a plurality of loud speakers in concentric arcs, those nearest the reference point l4 being designated by the number 40, the next row'by the number and the next row by the number 42.

Where it is desired to reproduce music with fidelity, the reproductions of these microphones will .be timed to reinforce the sound waves coming from the stage, and for this purpose the reproductions will be delayed to time them to bring them into phase with the air-borne waves. For this purpose, the leads 32 and 33 from the mixing amplifier 3| are carried through an acoustic reservoir 44 and van amplifier 45 to feed the loud speakers 40, and a second acoustic reservoir 38 and an amplifier 4-! feed the loud speakers "41, and a third acoustic reservoir 48 and amplifier 49 feed the loud speakers 42. The acoustic reservoir 44 will be adjusted to delay the reproductions by the loud speaker Ill by precisely the amount of time which is required for the sound to reach the position of the loud speakers 40', so that the reproduced sound will ice in exact phase with the air-borne sound. The acoustic reser- Similarly, the acoustic reservoir 21 will delay 4 voirs 4B and 48 will provide a correspondingly greater delay, and thus each group of loud speakers produces its own reproduction in exact phase with the airborne sound.

This construction, therefore, produces an effect at any point in the auditorium, having the complete harmony of the instruments reproduced in synchronism and having all the reproductions and the original sound united to form a harmonious result.

Since certain-changes may be made in the above construction and different embodiments of the invention could be made without departing from the; scopethereof, it is intended that all matter contained in the above description or shown in theaccompa'nying drawing shall be interpreted as illustrative and not in a limiting sense.

It ,is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

A etheatre' sound amplification system, comprisingia' plunality of spaced microphones, means for combining the Variables from said microphones, including means for adjusting the timing of said microphones to bring them into synchron'ism, and means for distributing the variables so produced to a plurality of spaced loud speakers, incmdingme'ans to adjust the timing "to each loud speaker to :bring the reproduced sound into synchronismwith air borne sound.

'2. Atheatre sound amplification system, comprising a plurality of spaced microphones arranged in: groups in concentric circles about a reference point, means for combining the sound variables coming from said groups, including mean for delaying each variable by an amount inversely corresponding to the distance from the microphones to the reference point, means for distributing the combined variable to a plurality of spaced loud speakers arranged 'in concentric circles from the reference point, including means toddelay the timing to each group directly as its distance from theref'erence point.

3. In a sound amplification system, in combination, a plurality of microphones arranged in groups :atdifierent distances from I34 point of reference; an acoustio'reservoir for each group, means 'conn'ectingthe microphones in each group to make a, record on one of said acoustic reservoirs, and means for reproducing a variable from each record after a time delay corresponding to the locationof the group from the point of reference, and means for uniting said reproductions.


REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'ITENTS Number Name Date 1,358,053 Bascom Nov. 9', 1920 1,365,410 Egerton Jan. 11, 1921 2,137,032 Snow Nov. 15, 1938

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1358053 *Dec 17, 1917Nov 9, 1920American Telephone & TelegraphTelephone system for auditoriums
US1365470 *Jul 26, 1917Jan 11, 1921Western Electric CoWave distribution
US2137032 *Sep 30, 1936Nov 15, 1938Bell Telephone Labor IncSound reproducing system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4485484 *Oct 28, 1982Nov 27, 1984At&T Bell LaboratoriesDirectable microphone system
US8243951 *Dec 15, 2006Aug 14, 2012Yamaha CorporationSound emission and collection device
US9049504 *Jul 9, 2012Jun 2, 2015Yamaha CorporationSound emission and collection device
US20100166212 *Dec 15, 2006Jul 1, 2010Yamaha CorporationSound emission and collection device
US20120281854 *Jul 9, 2012Nov 8, 2012Yamaha CorporationSound emission and collection device
U.S. Classification381/66
International ClassificationG10K15/08, G10K15/10
Cooperative ClassificationG10K15/10
European ClassificationG10K15/10