US2020166A

US2020166A - Sound reproducing apparatus

Info

Publication number: US2020166A
Application number: US12551A
Authority: US
Inventors: William O Swinyard
Original assignee: Hazeltine Corp
Current assignee: BAE Systems Aerospace Inc
Priority date: 1935-03-23
Filing date: 1935-03-23
Publication date: 1935-11-05
Anticipated expiration: 1952-11-05
Also published as: BE414489A; AT149923B; GB459003A; NL44803C; FR804770A; CH191887A

Description

Nov 5, 1935. I w b. swlNYARD V 2,020,166

*jjM

SOUND REPRODUCING APPARATUS Filed March 25, 1935 ATTORNEY.

INVENTOR.

Patented Nov. 5,1935

, sormn nmonucr'so mans-ms WilliamO. swlnyarddlaysideiltfnamignorto Haseltine corporation. a corporation of Dela- A plication M as. loss, serial a... 1:351

' 10 claim. (01. lei-s1) This invention relates to an improved highfidelity sound reproducing apparatus andvis particularly concernedv with sound reproducing apparatus of the type used in connection with radio 5 broadcast receivers and the like. r

,l'or'the most satisfactory reproduction of sound there must be a high degree of fidelity of reproduction and uniformity of distribution, that is to say, the sound waves of the various frequen- L cies must be uniformly reproduced and propagated with a uniform distribution throughout the room or auditorium into which such waves are radiated, and there should be a uniformity of effectiveness of the various sound waves through- 5 out the audible frequency range, without distor-- tion.

In order to obtain such satisfactory reproduc- 'tion, certain problems are involved due to certain peculiarities in the behavior of the sound waves 0 which are radiated by reproducers of the type now generally used, and to effects which result from the physical nature of certain parts of the reproducing apparatus employed.

It. is a well-known phenomenon of acoustics 5 that sounds of relatively high pitch. that is, sound waves of relatively short wave lengths and high frequencies, which are radiated from a relatively large area cone or diaphragm type of re- I producer or loudspeaker'i such as is now generally used in radio-broadcastreception), as well as in some instances from loudspeakers of the horn type (such as were formerly in general use), tend to be propagated substantially as a beam. in a head-on direction from the diaphragm,

; whereas sounds of relatively 'low' pitch, that is.

of relatively great wave lengths and low frequencies, are propagated substantially spherically. The consequence of thme phenomena has been a non-uniform distribution of the sound n waves throughout the response area. or reoeption room, characterised by a predomination of the sounds of higher pitch in locations directly in front of the reproducim apparatus and a pre-' domination of the sounds of lower pitch in the i5 adiacentlocationsr w Itisalsowellknownthatwhereasoundcav- -ityorrecessisemplored;thrcughwhichsound waves are radiated from the reproducer, parallel surfaces and o'pposins'parallel so vided by such cavity. in thepathfofthesound waves, will result, respectively. inreflections and refractions of such sound-waves. which-in turn result in the setting up ofinterference-patterns and in norl-imiformity of-eifectlveness of the pro--v ss variouswavestbrousheuttheauiiblera seof frequencies. One explanation of these results is the tendency of two or more waves, which are either so reflected or' so refracted as to arrive simultaneously at the same location, to either neutralize or reinforce each other, according ,to whether .they are so related as to add or sub- .tract at the location under consideration. The

fldelity of the reproduction of the various sound waves at different locations is thus affected by the inherent structural characteristics of the 1' sound cavity of the reproducing apparatus employed;

v his the object of this invention to provide an improved high-fidelity sound reproducing apparatus, whereby sound may be reproduced and u propagated with uniformity of distribution of the waves of various frequencies throughout the area into which such waves are radiated.

A further object is to provide an apparatus of. the character aforedescribed whereby the varigo ous sound waves reproduced throughout the audible frequency range will be free from distortion and the fldelity of the reproduction thereof will be uniform at all locations for which the apparatus is designed to provide reception. g5

Various other and further objects of and ad vantages achieved by the present invention will be apparent from the following description taken in connection with the accompanying drawing, wherein there is illustrated, by way of an examas pie. an apparatus embodying the invention.

. In accordance with this invention there is provided a sound reproducing apparatus which includes a sound cavity, through which cavity a reproducing device. such as a loudspeaker of the as relatively large area cone or diaphragm type, is adapted to radiate sound waves. in combination with a sound wave deflector. This deflector is disposed within the cavity. and extends transversely across the path of the sound waves therem through, and thereby serves to diffuse the sound waves of relatively higher frequencies which would otherwise tend tobe propagated substantially as a beam in ahead-on direction. The deflector. thus effects a substantially even distributim of the waves of the various frequencies throughout. the response area. 7

Further in accordance with this invention. the walls of the sound cavity and-theconflguration ofthedeflectoraresorelatedastoavoidpar-go oriparallel unsound cavity, thus substantially the undesirableinterference from reflections and 'refractions described above. 1 V lnthe luaper-u upper portion I I in a suitable well-known manner.

Below this apparatus a rectangular opening I! is provided in the front wall of the cabinet, from which wall extends a sound cavity, as indicated generally by the numeral II.

The cavity ll is deflned-by a rear wall such as a baflle ll, which slants in an upward and rearward direction from the lower edge of the opening, at an angle of approximately 10 to 20 degrees from the vertical, triangular side walls iS-il which converge rearwardly from the vertical side edges of the opening, and a top wan l8 which I slants in a rearward and downward direction from the upper edge of the opening. The rear edges of the walls I! and II engage the baille I4 and are suitabb-secured thereto, by brackets (not shown) or in any other desirable manner.

An opening ll is formed in the bane It at the central portion thereof and a sound reproducer or loudspeaker 2|! is disposed behind the baille opposite the opening. The reproducer is preferably of the type having a moving coil which drives a conical diaphragm of relatively large area, its diaphragm 2| suitably engaging the bane around the margin of the opening, with its axis perpendicular to the plane of the baiiie so that sound 'waves radiated by the reproducer will be propagated through the opening and through the sound Among other useful purposes, the sound cavity serves to provide an additional desirable amount of load on the diaphragm and to amplify the sound waves in accordance with well known principles. While the sound cavity II has'been illustrated and described as being open only at the front, it is to be understood that, in certain instances, certain other walls, such as the side walls I, may be omitted, it only being necessary that there shall be formed a recess unconfined or semi-confined space eflective to load the sound reproducing device, and the term "sound cavity" as used herein is to be so construed. The angle of the baflle is not critical but is preferably of such' degree that the axis of the cone will be directed toward approximately where the head of a listener in the center of a room of average size will be.

A deflector, indicated generally by the numeral 22, is provided within the sound recess. The deflector comprises a pair of plate-like-members 23-23 cooperating to form a dihedral angle with the vertex thereof extending across the opening l9. The deflector is substantially coextensive with the sound cavity. The side members of the deflector may be cut to conform to the walls of the sound cavity and so that their front edges lie in the plane of the front wall of the cabinet.

The dihedral angle of the deflector, while in the approved embodiment illustrated being approximately degrees, is not critical but in practice may be varied within limits of approximately 60 to degrees. according to the requirements 'of the particular embodiment, considering the position of the loudspeaker in the room where the same is to be used. It is within the contempla-. -tion of the invention-taco construct the balls that its members may be adjusted to vary the. degree of their angularity, andfor such a construction any suitable hinge or pivoting arrangement may be employed.

By virtue of the tapered effect of the deflector, 4 it .will be apparent that pathways are provided at the sides thereof within the cavity which are of varying width from top to bottom. Further, the shape and position of the deflector, together with the shapesand relative angular positions of the walls of the cavity, including the baille.

; provide a passageway, through which the sound waves are propagated, wherein there are no parallel surfaces and no opposing parallel edges.

In the operation of the apparatus, the audio- 1,

frequency or sound waves will be radiated from the diaphragm through the sound cavity, and

the waves of relatively high frequencies, which naturally would tend to travel substantially as a beam from the diaphragm, will be deflected by 2 the walls of the deflector members and so diffused throughout the receiving room as to provide a sub- I stantially even distribution thereof. By virtue of the shapes and relative positions of the various v surfaces and edges of the sound cavity and battle, 2 there will be substantially no interference from reflections or refractions of the waves. The-slanting position of the bailie and the axis of the: diaphragm will serve to eflect a propagation of the sound waves in an upwardly slanting directionso 3 as to provide the maximum eflectiveness at the most desirable location, that is, in a region elevated from the relatively/low position of the reproduce-r or in aregion approximately at the heads of listeners in the receiving room. In the completed apparatusa loosely woven screen or tapestry may, if desired, be provided over the opening l2, to protect the deflector and cavity.

improved apparatus embodying the present invention, it will be apparent that many and various changes and modifications may be restorted to, as to the manner of utilization of the method 4 and as to the form, structure and arrangement of the parts of the apparatus, without departing from the spirit of this invention, and it will be understood that all and any such changes and modiflcations are contemplated as a part of this inven- 5 tion, as defined in the appended claims.

What-is claimed is:

1. A sound reproducing apparatus comprising a sound cavity of non-uniform depth having an open front in a vertical plane, side walls and a 5 rear wall slanting relative to said vertical plane,

said rear wall being provided with an opening centrally. therein, a sound radiating device mounted behind said rear wall so as to radiate front plane, said surfaces being angularly disposed so as to disperse horizontally a beam of 6 sound radiated from said device through said 2. A sound -'reproducing apparatus comprising a sound cavity of non-uniform depth having an open front in a vertical plane and a rear wall I provided with an opening centrally therein, a

soundradiating device mounted behind said rear wall so 'as to radiate a beam of sound through said opening, and a sound deflector comprising tapered surfaces shaped t'oconform to the 11011- I uniform depth of said cavity and having their rear edges extending across said opening and their front edges substantially in said front plane. said surfaces being angularly i posed so as to disperse horizontally a beam of sound radiated from said device through said opening.

3. A sound reproducing apparatus comprising a sound cavity having an open front in a vertical plane. side walls and a rear wall slanting relative to said verticalplane, said rear wall being provided with an opening centrally therein. said cavity thereby being of varied depth, a sound radiating device mounted behind said rear wall so as' to radiate a beam of sound through said opening, and a deflector fitted into said cavity.

said deflector conforming to said varied depth of said cavity and providing surfaces of tapered angular shape having longitudinal rear edges extending across said opening and front edges substantially in said front plane and said surfaces being angularly arranged so as to disperse horisontally. a beam of sound radiated from said device through said opening.

4. A sound reproducing apparatus comprising a sound cavity having an pen front in a vertical plane. rearwardly converging side walls and a rear wall slanting relative to said vertical plane and provided with an opening centrally therein, said cavity. thereby being of varied depth diminishing from top to bottom, a sound radiating device mounted behind said rear wall so as to radiate a beam of sound through said opening, and

a deflector fitted into said cavity, said deflector.

conforming to said varied depth of said cavity and providing surfaces of tapered angular shape having longitudinal rear adjoining edges extendacross said opening and front edges converging from top to bottom and disposed substantiallyin said front plane, said surfaeu being thereby angularly arranged so as to disperse horizontally a beam of sound radiated from said device through said opening;

' 5. A sound reproducing apparatus comprising a sound cavity symmetrical with respect to a vertical 'plane. having an open front in a vertical plane normal to the plane of symmetry. side walls disposedinnon-parallelplaneaarearwallina non-vertical plane normal to the plane of symmetry and provided with an weningcentrally therein. a sound radiating device disposed behind saidrearwallandadaptedtoradiateabeamof whereby a beam of mi radiated from said device through said opening will be dispersed horisontally by said deflector.

6. A high-fidelity sound reproducing apparatus comprising a sound cavity including as the rear wall thereof a baille slanting at an angle to the vertical and, having an opening formed therein,

a sound reproducing device including a conical diaphragm disposed at the rear of said cavity -with its axis Perpendicular to the plane of said is baiiie and coincident with the center of said opening and adapted to radiate sound waves through said opening and through said-cavity; and deflector means disposed within said cavity extending transversely of said opening. is 7. A high-fidelity sound reproducing apparatus comprising a sound cavity having a flat rear wall provided with an opening; a sound reproducing device disposed behind said rear wall and arranged to radiate sound waves said openso ing and through said cavity; and a deflector within said cavity having a pair of substantially flat surfaces angularly arranged with adjoining edges thereof extending transversely of said opening.

a. A high-fidelity sound reproducing apparatus comprising a sound cavityhaving aiiatrea'rwall provided with anopening: a sound reproducing device disposed behind said rear wall and adapted to radiate sound waves through said'opening and so through said cavity;- and a deflector having a pair of substantially flat surfaces. an edge of one of said surfaces adjoining an edge of the other of said surfaces to provide a tapered deflector. and said surfaces being angularly arranged with as their adjoining edges extending transversely of 8816 e 9. A high-fidelity sound reproducing apparatus comprising a sound cavity having slanting upper, side, and rear walls. said rear wall'providing s40 sound baile and having an orifice formed there-,

in; a sound reproducing device adapted to radia'te sound waves .through said opening and throwh'said cavity; and apiurality of sound wave deflecting members angularly arranged withinsaid cavity and providing no parallel surfaces within said cavity.

10. A high-fidelity sound reproducing apparatus comprising a sound cavity having slanting upper,side,andr earwalls.saidrearwallpro-lo vidingasolmdbailleandhavinganoriflceformed' therein: a sound reproducing device adapted to radiatesoundwavesthroughsaidweningand throughsaidcavitnandapluralityotsound wave deflecting members arranged within said cavity, with no parallel iedgesi'ormedbythewallsofsaldcavityandsaid wit-um o.