US 2468721 A
Description (OCR text may contain errors)
April 26, J. VOLKMANN 2,468,721
EARPHONE SOCKET AND NOISE SHIELD Filed July 9, ,1945 2 Sheets-Sheet 2 Patented Apr. 26, 1949 UNITED STATES EARPHON E SOCKET AND NOISE SHIELD John Volkmann, Cambridge, Mass, assignor to the United States of America as represented by the Executive Secretary of the Office of Scientific Research and Development Application July 9, 1945, Serial No. 604,075
This invention relates to communication equipment and more particularly to an earphone socket to be used in conjunction with headbands and aviation helmets in supporting receivers at either side of the head.
In addition to its principal function of supporting a receiver, an earphone socket may also serve to provide acoustic insulationin other words, may constitute a noise shieldespecially when held rather tightly against the side of the head. It has been found in practice, however, that continued application of pressure transmitted through the socket against the ear and the head irritates nerves, interferes with blood circulation and may cause a great deal of discomfort. It is therefore desirable to maintain the socket mem-- ber firmly in place While at the same time preventing discomfort.
I have discovered a novel earphone socket and noise shield structure which, from a comfort standpoint, is relatively independent of excessive pressure exerted by either an aviation helmet or a headband. An important feature of my earphone socket comprises an integral construction made up of two variants of elastic manually-deformg5 able material including an outer stretchable shell or casing of relatively stiff material, and a compliant liner secured at the inside of the shell. The shell, by reason of its mass and stiffness, provides for good acoustic insulation. The compliant liner, When firmly held against the head, cooperates with the shell in achieving acoustic insulation by further providing a tight circumaural seal without discomfort.
Another feature of the invention consists in the shell member being formed with an outspread skirt having thin tapering sides which are so inclined outwardly as to improve flexibility and to enable the extreme outer parts of the socket to lie within a space very close to the head and to more readily conform to irregular contours at all points, both in front and in back of the outer ear, as well as above and below the ear.
Another feature of the invention consists in the shape of the compliant liner which is so des gned that it offers a pocket for receiving? and shielding the more rigid sensitive cartilage portions of the outer ear, while selectively contacting and lightly pressing against the relatively yieldable non-sensitive portions of the ear, thus providing for a high degree of comfort and excellent acoustic insulation.
Still another feature included in the compliant liner consists in a filler portion for reducing the volume of air between the socket body and the ear auriole, to produce better acoustic sensitivity.
The socket is also characterized by simplified construction, ease of manufacture, adaptability to headgear, cheapness and various other auvantages.
Specifically, it is an aim of the invention to enable the production of the socket in one piece 5 with a shell part of a moderately flexible elastic body which will include the receptacle for se curely and protectively holding the earphone removably by snap fit manipulation of the socket, while using in the head-contacting parts highly 1o yieldable molded sponge rubber for chamber shaping, for comfort, and for improved sealing against external noise. Sponge rubber is rather delicate, easily torn, worn or abraded in the quality best adapted for maximum deformation \with a given pressure, as intended, and it can not be satisfactorily used alone as the complete receptacle and retainer for the receiver element and as a head-fitting auriole and sealed chamber, with assurance of safe retention of the receiver. It also would have to be too bulky in all parts for convenient accommodation in helmets or head band sets, or in tank turrets and other confined situations, as Well as being excessively liable to damage in handling and shipment. Therefore, it is sought to obtain the benefit of sponge rubber head-contacting parts Without materially greater bulk of the material as compared to the more rigid materials of prior receiver mountings.
In such devices it is desirable in the interest of protection of the earphone from phsyical and electrical shock; to assure complete closure of the ear chamber against external sound, and to minimize origination of interfering or confusing frequencies in the socket, by vibratory movements of the receiver under shock, while at the same time giving the wearer a maximum of comfort, to form the whole socket piece of more or less soft rubber. However, for satisfactory security in retention of the earphone While permitting its ready removal and replacement, a quality of rubber is required which is not adapted to the production of the proper quality of ear and head contacting parts. One attempt to remedy this is shown in my prior Patent No. 2,403,418.
But I have discovered that a notable further improvement in sound exclusion and comfort is obtainable by using integrated dissimilar distortable rubbers in the receptacle and head- 5 engaging parts, and in changing the cushion function in the socket resulting upon coengagement of the device with the head.
As one step, it is sought to avoid a narrow bearing between the rim and head involved in some prior devices and obtain a greatly widened head contact without such bulk in the material as had heretofore been involved in broad ear pads of comparable accommodation capability.
Accompanying this improvement, it is the aim to permit much reduced pressure per unit of area on the head surfaces engaged, at the same time that improvement is achieved over the benefits of prior devices in effective sound exclusion and in permitting such free accommodation of the ear that the ear may be in its normal position and form for acute hearing.
In the accompanying drawings, wherein the device is shown in actual size,
Fig. 1 is a perspective view of the earphone socket member of the invention;
Fig. 2 is an inner side elevational view of the socket;
Fig. 3 is a rear elevational view of the socket;
Fig. 4 is an outer side elevational view;
Fig. 5 is a front elevational View;
Fig. 6 is a plan cross sectional view taken on the line 6-6 of Fig. 2;
Fig. '7 is a plan cross section taken on the line 71 of Fig. 2;
Fig. 8 is a plan cross section taken on the line 8-8 of Fig. 2;
Fig. 9 is a vertical cross section taken on the line 9-9 of Fig. 2; and
Fig. 10 is a View in side elevation of the outer ear.
The drawings illustrate a preferred form of socket which may, for example, support an earphone such as the ANB-H-l or ANB-H-IA types of U. S. Army and Navy earphones, or other forms of receivers. It is to be understood, however, that various changes may be resorted to, as in the means of attaching the socket to earphones, in the size and proportions of the various elements of the earphone socket, in the choice of materials of which the socket is formed, and in various other respects.
The general plan of the earphone socket of the invention includes an outer shell or casing member 2 of generally annular form in which there may be introduced and supported a receiver, and an inner compliant liner or facing l8 which functions to encase the outer ear and engage against the side of the head. The outer shell is preferably formed of a solid rubber or other moderately soft pliable material, but adapted to afford sufficient relative stiffness, while the compliant liner is constructed of a much softer material such as sponge rubber, to provide increased cushioning effect. The overall size of the socket member is so chosen that it completely surrounds and overlies the outer ear when pressed against the head by means of a headband, an aviation helmet or other suitable means.
In the case of the socket being used with a headband, it should be observed that one conventional practice consists in attaching the extremities of the headband directly to two identical earphones, one applied to each ear of the wearer. Pressure is then transmitted through the earphones and socket to maintain the socket members firmly against the sides of the head. When it is desired to employ an aviation helmet, the socket may be attached to the helmet as for example by the prior practice of a fabric skirt molded into the shell or other portion of the socket and providing a margin which can be stitched to the helmet. Various other means of attachment also may be employed.
Considering the socket member in greater detail, numeral 2 denotes an outer shell or casing (Fig. 1), consisting of a cuplike member having a planiform back wall with a central large opening 4, as may be more clearly seen from an inspection of Figs. 6-9 inclusive. The shell 2 has a flat outer annular surface 6. Closely inward of the annular surface 6, the shell is recessed to form a groove 8, which extends parallel to and beneath the annular surface 6 to form an overhanging phone-retaining flange portion In, and in spaced relation to the flange portion l0, an inner parallel small and thin rim or stop flange I2. The opening 4 provides a space for receiving an earphose which may be snapped into place by stretching the thin flange l0 and urging the rim of a conventional biscuit-shaped earphone into the annular groove 8. This provides a convenient means of inserting and removing an ear phone in the socket member.
In Fig. 4 I have shown the outer side of the shell 2. It will be observed that the annular surface 6 constitutes a part only of the overall width of the shell and that there occur continuous variously inclined sides which fall away from the annular surface 6 all the way around this portion of the shell. Thus, in Figs. 3, 4 and 5, it will be noted that the shell member is constructed with encircling continuous outspread skirt or wall 15 having a low front inclined side l4 and a high rear inclined side 16 of greater extent and sharper pitch than the side H, and of less extension parallel to the plane of the surface 5 as is further illustrated in Figs. 6 and 7. The angle of inclination is least along a line passing through the center of the front side 14, and increases in steepness along the upper and lower sides of the shell, reaching a maximum along a horizontal line passing centrally through the rear side Hi. The inclined sides of the shell are also tapered to terminate in a relatively thin edge as shown in Figs. 6-8 inclusive. This edge lies in a plane which is convergent forwardly with respect to the plane of the annular surface 6. The shell thus has a generally frusto conical form.
As a result of this shell construction, the socket member is adapted to fit snugly across the cheek bone in front of the outer ear, and also to fit in a different plane along those portions of the skull occurring in back of the ear while the receiver is in a different plane, best adapted to direct its sound frequencies toward the concha and auditory canal. The thin tapering edge construction of the shell permits the shell memher to be located Very closely to the skull without crowding the ear and thus provides better acoustic insulation while preserving the comfort of the wearer. In addition, the thin tapered edges provide a pronouced torque flexibility which allows the outer edge portions of the skirt IE to be flexed to fit varying head shapes and sizes,
. even though a relatively stiff material is being employed, as compared to that in the liner.
At the inside of the shell 2, the small inner rim portion [2 presents a relatively flat surface which gradually merges with the tapered inclined sides. Against this relatively flat annular surface and the inclined sides is mounted the compliant liner I8, consisting of a mass of relatively soft material such as sponge rubber molded to the form indicated approximately in Figs. 1, 2, and 6 to 9. The liner member may be secured by adhesive or other convenient means, and is formed with an opening 20 which is opposit and coaxial with the opening 4 through the shell 2. The inner edges of the opening 20 have been formed by allowing the sponge rubber material of the liner to project beyond the inner rim l2. There is thus provided a flat annular surface 22 against which the inner face of an earphone is allowed to rest.
The compliant liner also presents a broad sealing rim 24 which extends all the Way around the inclined sides of the shell and an effective cushion which projects beyond the tapered edges of the shell. The sealing rim is of a gently rounded shape from its outer to its inner surface boundaries, as may be seen in Figures 6 to 9 inclusive, and varies in thickness as it passes around the edge of the shell member. Thus, at a horizontal line passing below the center of the front side I4 of the shell member (Fig. 2), the sealing rim is formed with an indentation which accommodates the cheek bone and auriculares superior and anterior. As it extends upwardly (Fig. 2), the sealing rim increases in thickness as at 21 to provide a relatively more bulky portion for engaging against the head at the temple region and extending rearwardly just above the outer ear. Continuing on downwardly at the rear, the sealing rim decreases in width and slightly in thickness, to form an indentation 29 to conform to the rounded bony prominence and auricularis posterior, which lies immediately behind the outer ear. There below the sealing rim increases in width and thickness as at 30 (Figs. 2, 5, and 9), to fill in the space directly below the ear in the region of the mastoid process and then finally again decreases in thickness for the latter, at 3| to merge with the original forward part 25 above-noted, as further shown in Figs. 6-9 inclusive.
The curvature and variation in thickness of the rim provide an exceedingly effective circum-aural seal. Moreover the compliant nature of the liner member together with the relatively broad, nearly flat area of contact of the rim due to its cross sectional shape allows the socket as a whole to be firmly pressed against the skull and maintained under adequate pressure, by the force normally exerted by a conventional headband or an aviation helmet, for extended periods without causing loss of circulation or discomfort.
Generally inward of the zone comprised within the rim, and more or less directly in back of those portions of the sealing rim 24 occurring along the rear side [6 of the shell, the liner I8 is recessed to form a semi-aural cavity 26. The cavity generally corresponds in shape peripherally to the form of the helix of the ear, and is of a size sufiicient to receive, and to afford a slight clearance for, and around, the helix of the car when the socket is held against the head. Thus the cavity 26 approaches its greatest width along a horizontal plane passing through the horizontal central axis 32 (Figs. 2 and 4) of the socket as may be noted in Fig. 7. At points above and below, the cavity decreases in width and gradually terminates at the top and bottom of the socket adjacent the forward roots of the helix and the lobe of the ear.
It is pointed out that the anti-helix and antitragus portions of the outer ear (Fig. 10) are relatively stifi sensitive cartilages which if bent to any appreciable extent in a direction toward the head will, in a short time, develop sharp discomfort. On the other hand, the helix and lobe portions of the ear are relatively yieldable and may be lightly pressed against the head and held there for extended periods without any discomfort developing.
An important function of the aural cavity 26 is to permit application of pressure selectively to the helix and lobe portions of the ear, While carefully shielding the anti-helix and anti-tragus from any pressure whatever. In this way, a maximum of comfort is achieved, irrespective of presbient external sound to the ear.
sures applied on the socket, and yet an exceedingly compact arrangement of the ear and socket against the skull is obtained which further adds to the improved acoustic insulation of the socket.
The compliant liner member further includes means for reducing the volume of air which is present between the earphone and the ear. Since the ear normally extends outwardly in an asymmetrical position with respect to the side of the skull, and since bending of the anti-helix and anti-tragus portion is required to be avoided, for the achievement of minimum volume, the inner face of the earphone must necessarily lie in a plane which is asymmetrical or offset with respect to the side of the skull. The liner member is so designed and arranged with respect to the shell that an offset positioning of the microphone is obtained. This provides an efiective decrease in volume of air.
I have also provided a somewhat Wedge-shaped filler portion 28 which consists in an additional padding of sponge rubber extending rearwardly from the front edge [4 of the sealing rim toward the opening 20, and decreasing in thickness, as may be more clearly seen in Fig. 1 and Fig. 2. When the socket is held against the head, the filler portion largely occupies the space not already occupied by the outer ear, thus further reducing the volume of air present in the cavity 26. The immediate advantage of reducing the volume of air in this manner is to substantially improve acoustic sensitivity, thus improving efliciency of earphones generally when employed with this type of socket member. By reducing the volume of space within the chamber, phase differences in transmitted signals and reflections are reduced.
It should be observed that this filler portion 28 improves the comfort features of the socket by resting lightly against the tragus and antitragus. Also, the filler portion together with adjacent inner surfaces of the liner improves acoustic in sulation by forming a secondary aural seal which very substantially reduces transmission of am- The line of secondary sealing in this case extends from a point directly in front of the tragus upwardly and then rearwardly across the ear above the tragus to the anti-helix. From here the line of this sealing follows a curving ridge formed by the anti-helix, then turns downwardly across the anti-tragus and finally curves upwardly to the point of starting. The rim 24, as a primary seal, is outwardly of the secondary seal mentioned and is a continuous annular one.
That portion of the liner which occurs along the edge 16 of the shell and which overlies and defines the cavity 26 also acts as one kind of filler to reduce the total included volume of air and in addition, supplemented by the flexing of the tapered edge of the wall or skirt l5 has some bending compliance which facilitates sealing accommodation to the irregularities of the skull in back of the ear.
The two materials of the earphone socket are essentially integral and may be formed by some suitable method as molding or other procedures, and may then be joined together by means of an adhesive such as rubber cement, plastic, or similar material. It is pointed out that the two-piece character of the socket tends to facilitate molding operations and thereby to reduce the cost and lessen the time required in the manufacture of such devices.
In the functioning of the sealing rim, it will be appreciated that by reason of the thinness of the liner material as well as its great breadth, it will transmit a substantial pressure from the head to the outer parts of the skirt l5, and, due to the thinness of the skirt edge portions, these will be flexed simultaneously with the compressive deformation of the liner material. Thus, by reason of this flexure, a translative movement of the rim portion relative to the receptacle and headphone occurs as the rim accommodates itself to the higher parts of the head surfaces engaged.
In the use of such devices in aircraft, armored vehicles (tanks) and other military uses, conventionally cushioned headphone receivers oscillate on the head of the user by rapid or occasional translative movements due to shock and abrupt movements of the body of the wearer, such phone motions produce alterations of sound or articulation, in signals (possibly includes partial doppler effects) and it is an advantage of the present invention that the skirt, with its rectilinear cone elements extending from the receptacle to the head, serves as a shoring to buttress the receiver against tendency to such relative movements in relation to the auditory canal so that the mentioned liabilities are minimized.
The composite socket member, therefore, provides a convenient earphone support having excellent sound insulation effects. A high degree of comfort under extended periods of wear is insured and greatly improved acoustic sensitivity is obtained.
1. A socket member for an earphone comprising a cup-shaped shell having an earphone receptacle adapted to receive and contract on a conventional earphone, and being of relatively stiff but manually compliant elastic material manually stretchable deformable to engage over and around and snap into contractile engagement with an inserted receiver unit, said shell having an opening formed therein for receiving therethrough when distended an earphone, a highly compliant liner member secured at the inner side of the shell, said compliant liner presenting an irregularly shaped sealing rim which extends all the way around the'shell and projects beyond the edges of the shell, said sealing rim having a rear portion spaced away from other portions of the liner to define an aural cavity for receiving the helix portion of the ear, said liner further including a filler portion which extends rearwardly from a front edge of the said sealing rim, said sealing rim constructed and preshaped to form a wide, nearly transversely fiat intaglio of the contours of the head underlying the rim to constitute a primary seal, said filler and rear portion of the liner being arranged and cooperating with the said aural cavity to provide a secondary aural seal about the tragus, anti-helix and antitragus portions of an ear.
2. A combined earphone-mount, guard, and noise shield, consisting of a body comprising a shell of relatively stiff but stretchable manually deformable elastic material having an opening therethrough one side of the body constituting a receptacle adapted to snap upon and around an earphone receiver when inserted therein, said shell at its opposite side having an auricle chamber of a size and form to receive loosely therein the external ear of a person, said chamber comprising an outspread substantially frusto conical skirt part siurounding and integral with said receptacle, tapered in thickness from its base to its periphery to form thin flexible edges, and an ex-- tremely compliant thin filling and facing cushion body united with the skirt to form a part of said auricle chamber and extending beyond the skirt edges, said skirt and facing body defining a generally annular pad, said facing cushion body having preformed irregularly shaped sealing surfaces approximating the intaglio of an annular area on the head of a person outwardly of and around the external ear and being of a size to receive the ear freely therein, said facing cushion body further including filler portions arranged to occupy space within said chamber in the shell between the auricle of the ear and the central part of said auricle chamber and part of an earphone when engaged in said receptacle, said filler portions being shaped to focus upon the auditory canal sound emitted in said chamber by the earphone and to improve acoustic sensitivity.
3. As an improved article of manufacture, a socket for head sets comprising a moderately deformable elastic rubber-like body having an open receptacle adapted to be stretched to hold a flat receiver tightly therein and having an integral outspread straight-element frusto-conical skirt wall surrounding the receptacle and tapered from its base to its periphery so as to be of major flexibility at its extreme edge portion, and a head-engaging lining and cushion part carried by the receptacle and skirt and consisting of an elastic material of extremely greater compliance and deformability than said body, said lining and cushion part having a thin wide, nearly fiat peripheral rim coextensive with the circumference of the skirt so that there will occur moderate depression and translative displacement of the rim parts by the head of a person when the socket is pressed against the head by a conventional headband.
i. The structure of claim 3 wherein said facing part is preshaped with approximate contours of head surfaces in intaglio.
5. The structure of claim 3 wherein the peripheral portion of said facing part is preshaped with an approximation in intaglio of head contours around the human ear as a continuous rim having a continuous head-engaging surface of a width throughout of not less than one-half an inch, and of slight transverse convex curvature so that a close approximation of a transversely flat fit of the facing and human head surfaces is effected by pressure of the headband, with great magnification of the transverse effective sound insulation impedance and whereby a minimum pressure per square unit of area is manifest on the head of the wearer.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,396,771 Minton Nov. 15, 1921 2,204,183 Hulin June 11, 1940 2,403,418 Volkmann July 2, 1946 2,407,731 Woodruff Sept. 17, 1946 2,423,355 Veneklasen July 1, 1947