US2301459A - Electric megaphone - Google Patents

Description

Nov. 10, 1942. A. J. YSANIAL 2,301,459

ELECTRIC MEGAPHONE Filed Dec. 28, 1940 2 INVENTOR.

RI- 50min! Patented Nov. 16,11

STATES rsNr OFFlCE nnncrmc maarnona Arthur J. Sanial, Flushing, N. I, 'assignor to Guided mop Qu tation, New York, N. Y., a

This invention is concerned with an electric megaphone by means of which sounds, such as which the loudspeaker unit a and the tubular extension 2 are'rnounted.

spoken sounds, supplied to one end oi the device issue from the other end in greatly amplified I volume.

An object of the invention is the provisionof a simply controlled, portable device for usein place of the ordinary megaphone and by means of which a speakers voice may be greatly amplilied and easily directed as required.

Another object of the invention is the provision in a single portable instrumentallty, of a combination microphone and loud speaker respectively associated so as not to cause any electrical interference therebetween when interconnected by means of an amplifier.

A more general object of the invention may be said to be the provision of an electric megaphone by means of which sounds delivered thereto may be greatly amplified in volume.

Other and more detailed objects of the invention will become apparent from the following detailed description of one embodiment thereof.

This invention resides substantially in the combination, construction arrangement and relaunit comprising this invention.

As illustrated in. the drawing, the complete A second annular wall forming member 8' is secured atone end to the support d and extends from that support back towards the support 5 but terminates short thereof, as clearly shown in Figure 1. The wall forming members 3 and ii define an annular space 5 which forms a reversely extending annular passage in communication with the passage through the tubular extension 2; Surrounding these elements is an outer cylindrical or other suitably shaped' housing l which with the wall member 3' forms another annular passage 8 which is in communication with the passage 5 around the end of the wall member 3'. At its other end the passage 8 is in communication with the atmosphere through the bell or flared end 9 oi the housing ll.

' nel is formed in a compact manner to provide the advantages and benefits oi the much larger construction which would result ir' 'they were placed end to end.

Preferably the passage at the base of the bell 9 is covered-with a, suitable porous or screen combination of the invention includes a megaphone unit made up of a microphone of any suitable type and a loudspeaker of any suitable type,

all enclosed within a housing constructed to provide a folded born for acoustically amplifying and directing the issuing sounds;

As illustrated, the device consists oi a loudspeaker unit 9, of any suitable type such as a permanent magnet form, provided with a horn consisting of a tubular extension 2 in the mouth phere.

of which is secured a support, without comannular tubular member! is secured to the end a of the tubular extension 2 in any suitable manher so as to enclose and seal the chamber within 55. oil by a porous wall I! which may be in member it, behind which the parts are hidden but without in any way interfering with the issuing sound waves.

interposed between the end wall of the housin l and the annular support 3, by means of an annular flange it, is a cylindrical housing i5 which is open at both ends.

The flange it is gripped between these members by rubber gaskets 2 and all of these parts may be secured together in any suitable manner, such as by means of bolts or rivets (not shown). By this construction the various compartments aresealed with respect to each other and with respect to the outer atmos- Mounted within the cylindrical housing I5 is a microphone I? of any suitable construction. The periphery of the microphone housing is enclosed within a tube i3 of any suitable material, such as a soft fibrous materiaL- The microphone housing i2 and the loudspeaker unit housing I,

- are spacedv apart and interposed between them in a thick disc or layer Ill of felt. Q.

likewise interposed between th'housing I and the microphone housing is a'gasket 4 of 'felt. The open outer end oi the housing I! is closed the form faces the open end wall of the housing I so as to be exposed to sound waves directed thereinto.

Otherwise the microphone unit is completelyhoused and sealed and is so mounted as to be as vices being spatially 180 degrees apart,- prevent acoustical feedback between the two.

' little subject as possible to disturbing vibrations.

It will likewise be seen that by reason of the gaskets IE and H, as well as fibrous tube l3. and .the felt wall H, the microphone is sound insulated from the various passages within the horn, and is also. isolatedv from mechanical vibrations induced by the loudspeaker unit in the entire structure, as well. Thus an important and novel feature of this invention is the space relationship between the'mi'crophone and the loudspeaker and the physical structure by means of which they are incorporated into one unit, so that mechanical.

and acoustical feedback between the two is eliminated.

Attached to the housing l at any suitable place as at the bottom, is a properly formed handle l9 provided with an'easily accessible finger operated switch 20 by means of which'the apparatus may be cut into and out of use.

The general combination is illustratedin Figure 2 wherein a portable amplifier of suitable type, such as a battery operated vacuum tube ampli- In order to attain the object of this invention in a practical way it is highly desirable that the loudspeaker unit be of the type whichis markedly directional The speaker and born to be of a type whichradiates most of thesound generated thereby substantially in a narrow cone from its mouth symmetrical with the axisof the horn. In view of the fact that the directivity of a loudspeaker tends to become less sharp at lower frequencies, it is important that the frequencies radiated by the electric megaphone be limited to those in the frequency spectrum which are sufficient to permit intelligible speech to be transmitted and yet are within the range of frequencies for which the horn maintains its highly directional properties. By using a sharply directional loudspeaker one of the important objects of this'invention is obtained. This ob- Ject, as previously referred to, is that of preventing acoustical feedback between the loudspeaker fier 22, is shown connected by a cable 2| with the necessary number of conductorsto the microphone unit. As illustrated this cable extends to the handle l9 and to the switch mounted thereon. From it the individual conductors may extend to and for connection to the microphone and loud?- speaker units in accordance with well knownpractice. I

Thus as will be readily understood, the micro-' phone will be connected through the cable. 2| to the input of the amplifier, while the loudspeaker will be connected to its output. The

switch 20 may control thecircuits in any suit-- able manner, as by simply interrupting the microphone circuit when open or byinterruptingf' the energizing circuits for the amplifier when open.. The details of circuit connection do not form any novel part of this invention.

From the-above description the nature and and themicrophone. Therefore, in addition to placing these two devices so that they are 180 degrees apart in space, a highly directional loudspeaker is employed, thereby minimizing any tendency to feedback acoustically. To re-emphasize the point, mechanical feedback through the structure of the device is prevented by thoroughly insulating the loudspeaker and micro phone from each other against the transmission of vibrations therebetween through the structure of the unit; The insulating structural features likewise serve to isolate the units from any direct airpath connections so as to contribute to the prevention of acoustical feedback.

It will of course, be apparent to those skilled.

in the art that in view of the fact that vacuum tube amplifiers of considerable amplifying power are available at the present time in small physrcal units, that'the amplifier may. readily be incorporated when desired directly in the electric megaphone unit, whereby all the apparatus of this invention may be incorporated, when it is practical, in a single-housing. From the above description it will be apparent tothose skilled in the art that the novel subject use of the invention will be apparent to those. I

skilled in the art. The userwill either carry the portable amplifier on his back or in his pocket, or-leave it on the ground if the cable 2! is long enough. The megaphone unit is held 7 preferably by the handle and when it is to be used the speaker closes the switch 20. With switchill closed sounds entering the opening in the housing l5 impinge upon the microphone causing it to translate the sound waves into .electrical current representations thereo These currents pass through the amplifier and then are supplied to the loudspeaker. unit '-I which acts to convert these amplified electrical currents intoreproductions of the original sound, but at magnified volume as they are projected from the bell of the unit. "Thus by means of this simple device the user speaking inordinary matter of this invention may be embodied in other specifically different physical forms and I do not, therefore, desire to be strictly limited to. -the disclosure as given for purposes of illustra- ,tion, but rather to the scope of the claims grant.-.

' ed me. a

What is claimed is: 1. In an' electric megaphone, the combination including a microphone and a loudspeaker,

- means for supporting said microphone and loudtones may project his voice in properly amplified volume in the desired-direction. As is obvious e the operation of the'apparatus is simple and indeed its use'is no more complicated than the .usual form of megaphone consisting of nothing more than, an elongated horn. The microphone and loudspeaker have been so associated that the sound waves may not be by-passed from one t the other and at the same time the. two-despeaker in back to back relation, and a housing for said units comprising a folded horn havlng an entrance and an exit, the entrance of said horn being connected to said loudspeaker and. said housing having an opening at which the microphone is positioned, the exit of said horn and the microphone opening being spatially dis-.

placed A 2. In an electric megaphone, the-combination comprising a. microphone unit and a loudspeaker unit positioned back-to back, a housing enclosing-said units and. having openings at opposite ends, said microphone beinsl'positioned opposite one of said openings,- and'a plurality of telescoped wall members within saidohousing' fQrm-. ing a continuous tortuouspath with said.. hous ing, the' innermost of said wall members being connected totheloudspeaker and the' ther oi,

2,301,459 said housing openings forming the terminaL1endof said tortuous path.

3. In an electric megaphone, the combination comprising a microphone unit and aloudspeaker unit positioned back to back, a housing enclosing said units and having openings at opposite ends, said microphone being positioned opposite-one of said openings, a plurality -of :teiescoped wail members within said housing forming a continuous tortuous path with said housing, the innermost oi said well members being connected to the loudspeaker and the other of said housing openings forming the terminal end of said tortuous path, an electric amplifier and circuits for interconnecting the microphoneand loudspeaker with the amplifier. I I

' ARTHUR J SANIAL.

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