Abstract:
A head-supported two-way communication system. The system combines a thin bstrate forehead or head-bone microphone, a noise filter embedding the microphone, a universal impedance matcher connecting the microphone to a two-way radio, an unobstructed and unfettered-access push-to-talk switch, and a pair of rigidly positionable noise protected speakers, all secured to a head-supported structure permitting proper location of the embedded microphone, the switch, and the speakers for a particular user and application.

Description:
GOVERNMENT INTEREST STATEMENT 
     The invention described herein may be manufactured and used by the Government of the United States of America for Government purposes without the payment of any royalties thereon. 
    
    
     INTRODUCTION 
     The present invention relates to communications and communications systems. More particularly, the present invention relates to a head-supported communication system providing high clarity two way radio communications in high noise, high hazard, and environmentally extreme conditions. 
     BACKGROUND OF THE INVENTION 
     Two-way radio communications under the best of conditions can be difficult, or at a minimum, problematical. Such communications are often erratic, intermittent, and subject to various forms of environmental and operational interference and disruption. This is particularly true where the elements of the communications system being used are secured within the confines of or upon the structure of a helmet or other type of head gear or head-supported structure. Such helmet-type or head-supported systems are commonly used in military applications involving high-noise conditions in the air such as helicopters and other types of aircraft, on the surface, such as tanks, air-cushion vehicles, and personnel carriers, and on or beneath the surface of a body of water, such as high speed boats, air-cushion watercraft, and submersibles. The above applications, both civilian and military, are not, of course, all inclusive. Likewise, other civilian applications include, but are not limited to, helmets or other head-gear for motorcycle, skydiving, motor boating, jet ski, personal watercraft, firefighting, video game, police work, voice recognition for computers, and hazardous materials applications. There are both civilian and military applications where a gas mask must be worn with a helmet with eye and face protection, without interfering in any way with communications between the user and another. 
     The environmental exposure to which a helmet or head-supported communication system may be subjected include high and low temperature, extraordinary shock and vibration effects during handling and use, high levels of audible sound, moisture, and toxic and chemically damaging agents. One of the best examples of an environment containing the broadest spectrum of challenging and extreme environmental factors is that of firefighting. The firefighting application demands the use of special apparel such as gloves, helmet liners, and face and eye protective elements that may contribute adversely to the use and operational effectiveness of a helmet communication system. 
     In existing art helmet or head-supported communications systems, conventional microphones are typically positioned on a boom in front of the user&#39;s mouth to pick up speech. In this location, the microphone will pick up ambient background noise including wind noise, breathing, and other external noise transmitted into and through the helmet. Additionally, a boom microphone is obviously subject to physical damage during handling and use by virtue of its exposed and unprotected location. It may also constitute a hazard to the user by virtue of its position near the user&#39;s face. If the microphone is of a type mounted directly to the helmet or gas mask, sound and vibrations transmitted through the fabric or material structure will be picked up as interfering noise. Such noise may completely drown out or obscure otherwise intelligible voice communications. Noise cancellation provided by special circuitry may be applied to the microphone output to achieve some degree of improvement. 
     Speakers used as earphones in helmets or head-supported communications systems are either affixed to the helmet or head-supported structure or placed on the user&#39;s head and plugged into an accompanying radio. Typically, in prior art systems, the earphones are not adequately supported and adjustable to provide user comfort, maintainable position, and effective performance in an operationally challenging environment. 
     SUMMARY OF THE INVENTION 
     It is thus an object of the present invention to provide a head-supported, high-clarity, two-way voice communication system for use in an operationally challenging environment. 
     It is yet another object of the present invention to provide a head-supported, high-clarity, two-way voice communication system for use in a high noise environment. 
     It is further an object of the present invention to provide a head-supported, high-clarity, two-way voice communication system capable of picking up voice sounds out of a wind stream. 
     It is yet another object of the present invention to provide a head-supported, high-clarity, two-way voice communication system providing for voice pickup through a combination of flesh and bone. 
     It is still another object of the present invention to provide a head-supported, high-clarity, two-way voice communication system providing for voice pickup through the user&#39;s forehead, behind the ear, or on the back of the head. 
     It is yet an object of the present invention to provide a head-supported, high-clarity, two-way voice communication system providing mechanical and ambient noise filtering barrier. 
     It is another object of the present invention to provide a head-supported, high-clarity, two-way voice communication system providing for virtually hand-free operation. 
     It is still another object of the present invention to provide a head-supported, high-clarity, two-way voice communication system having no intrusive or potentially injurious functional elements. 
     It is still another object of the present invention to provide a head-supported, high-clarity, two-way voice communication system having easily positioned, and position maintainable ambient-noise-filtered speakers for ear input to the user. 
     It is finally an object of the present invention to provide a head-supported, high-clarity, two-way voice communication system having a virtually hands-free, and unobstructed access talk-to-listen switching capability. 
     In addressing all of the recited objects, the present invention, the high noise communication system, is a combination of ambient-sound-filtered voice output and voice input elements adjustably and functionally positioned in a head-supported structure. The head-supported structure of the present invention is a head-mounted means for positioning and maintaining a forehead or other skeletal contact microphone assembly in functional contact with the forehead or other skeletal contact locale of the user, an impedance matching device in proximity to the microphone assembly to permit maintenance of a reliable, impedance-matched connection between the microphone assembly and a user-selected two-way radio, the speakers in rigidly adjustable juxtaposition with the user&#39;s ears, and a two-way switching element, such as an activate-to-talk switch positioned to provide unobstructed, unfettered access to a user wearing gloves and other protective garments that could otherwise be expected to interfere with activate-to-talk switching. An alternative switching element may be a voice-command-operated two-way switch. The switching element connects between the radio and the microphone to permit the user to communicate. Voice inputs to the user are received from the two-way radio via ambient noise-filtered speakers. The speakers are flexi-rigidly and adjustably secured to the head-supported structure using a flexible rod so that they can be adjustably positioned and maintained in position for a particular user. Once positioned, they require little, if any, further adjustment and remain spatially located to be non-interfering and non-intrusive to the user&#39;s activities, including ingress and egress to the head-supported structure. 
     These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial side view of one embodiment of the present invention in use. 
     FIG. 2 is a bottom view up into a helmet employing the present invention. 
     FIG. 3 is a partial side view of the microphone assembly of the present invention. 
     FIG. 4 is a partial frontal view of a helmet portion showing elements of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, it will be seen that the high noise communication system 10 comprises a head-supported structure such as the helmet 12, a microphone assembly 20, an earphone assembly 30, a activate-to-talk switch 40, and an impedance matching device 50. In FIG. 1, the head-supported structure is the helmet 12, in a configuration, for example, typically used in firefighting. Other means for supporting the communications components of the invention may be employed in different embodiments of the invention for different communications applications. For example, a rigid web-like structure similar to a helmet liner may be used. 
     The microphone assembly 20 is secured as shown in FIGS. 1 and 2, to the forward portion 14 of the helmet 12 in a location placing it immediately adjacent to and in contact with the forehead of the helmet wearer. The microphone assembly 20 comprises the microphone 21 embedded in a multi-layered assembly comprising an acoustic filter 22. Microphone assembly 20 can optionally be encased in a protective fabric which is not illustrated in FIG. 1 but is depicted in FIG. 3 as a fabric pouch 28. The acoustic filter 22 consists of at least two layers of elastic material of different density. Thus, as depicted in a preferred embodiment in FIG. 3, a cross-sectional side view of two layers 23 of high-density rubber-like material are alternated with two layers 24 of low-density foam-like material. The layers 23 and 24 may be physically bonded together. In addition, FIG. 3 shows a lead sheet 25 sandwiched between a foam layer 24 and the next adjacent high-density rubber-like layer 23. A centrally located cavity 26 is created in the outermost low-density foam layer 24. The cavity 26 is sized and physically configured to receive and retain a thin sheet lead receptacle 29 which, in turn, snugly accommodates and retains the microphone 21. The entire microphone assembly is totally covered by the fabric pouch 28. Electrical connection of the microphone 21 external to the helmet 12 is accomplished by means of the microphone lead 27, as depicted in FIG. 1. The lead 27 extends from the microphone 21 through the microphone assembly 20 through and along the interior surface of the helmet 12, secured thereto, until exiting from a rear area of the helmet structure. External to the helmet 12, the microphone lead 27 connects to an impedance matching device 50, such as an impedance matching circuit, the output of which is connected to a radio 60. As shown in FIG. 3, the impedance matching device 50 is encased by the lead sheath 52 except for an opening permitting the entry of the signal from microphone 21 and the exit of the impedance matched signal output to the radio 60. Depending on the physical structure of the helmet 12, the electrical lead 27 may be buried or embedded within the helmet structure or in special molded channels 13 therein. These channels may be structurally reinforcing elements of the helmet structure or wiring accommodations. It is obviously important to route and secure the electrical lead 27 in the helmet 12 out of the way so that it does not interfere with user actions and is not cut, broken, or otherwise disconnected. 
     This is true, of course, for any type of head support structure used. The earphone assembly 30 comprises speakers 31 affixed to mounting blocks 32 which are secured adjustably to flexible cable 33 by means of set screw 34. Each mounting block 32 has a hole extending centrally there through. One end of the flexible cable 33 extends slidably through the hole in each block 32 so that the earphone 31 attached to each block 32 can be vertically positioned on the cable relative to the wearer&#39;s ears. A threaded hole extends into the block 32 normal to the hole receiving the cable 33. The set screw 34 visible in FIG. 4 is used in the threaded hole to secure the cable 33 in the mounting block 32. Cable 33 is flexible enough to be formed to position the slidably attached earphones 31 adjacent to or in contact with the wearer&#39;s ears but rigid enough to retain its formed fit. Cable 33 is attached to the interior surface of the helmet 12 or other head-supported structure 11. In the embodiment shown in FIG. 1, the cable 33 is recessed in a channel 13 molded into the structure of the helmet 12 and affixed therein by adhesive or other bonding means. The earphones 31 connect to the radio 60 by means of the earphone lead 36. 
     The activate-to-talk switch 40 shown as a push-to-talk switch is affixed to the underside of the brim 15 of the helmet 12. The switch 40 is connected electrically to the two-way radio 60 which is secured to the wearer in a manner that assures its retention under all conditions of use. The configuration, size, and mechanism of the switch 40 and its location on the helmet 12 are such as to permit ease of use by a user wearing gloved or otherwise covered hands. For certain applications a voice-command switch can be used. 
     The impedance matching device 50 to which the microphone 21 is connected by electrical lead 27 permits impedance-matched connection of the microphone 21 to any HF, VHF, or SATCOM radio having an input impedance of 5 to 2000 ohms. The circuit 50 permits the microphone 21 to have the same output volume as the standard microphone designed for use with each radio used. The impedance matching device 50 is covered substantially with a thin metallic shield or sheath 52 to eliminate or minimize interference. 
     One embodiment of the helmet communication system 10 employees a microphone assembly 20 using a piezoelectric film microphone 21. The microphone 21 has a polyvinylidene membrane having a thickness of the order of 15 microns and is available from AMP SENSORS of Valley Forge, Pa. 
     The microphone 21 is embedded in one surface of the acoustic filter 22. The acoustic filter 22 in this embodiment is comprised of two layers of QUIET-MAT™ DSB-1 sound control material from Noise Reduction Enterprises, Marine Products Division, of Essex, Mass. This material is a composite of two layers. One layer is a 1 lb/Sq ft high-density barrier. This layer is laminated to a 1/4 inch thick foam decoupler. Two layers of the composite material are bonded using glue sheets to a thin lead sheet 25 approximately 1/32 to 1/16 inches thick sandwiched between the two so that the high-density sound barrier side 23 of one composite layer is in contact with one side of the lead sheet 25 and the foam decoupler side 24 of the other composite layer is in contact with the other side of the lead sheet 25. The two composite layers completely cover the lead sheet 25. The entire sandwich is optimally sized at 2.5 inch by 8.0 inch for a typical application. It is important that the filter 22 be at least this size to maximize comfort for the wearer and to assure minimum ambient noise input to the microphone 21. The layer of high density material 23 comprising one side of the sandwich is the side embedding the microphone 21 and thus, facing the wearer&#39;s forehead. The entire microphone assembly 20 is contained protectively in the fabric pouch 28. The protective fabric pouch 28 is fabricated from DARLEX™ fabric #3608 from Shawmut Mills of West Bridgewater, Mass. 
     The impedance matching device 50 used between the microphone 21 and the radio 60 is a pre-set adjustable gain impedance matching circuit which will automatically match the output of the microphone 21 to any HF, VHF, or SATCOM radio with an input impedance value ranging from 5 ohms to 2,000 ohms. The circuit operates with a voltage supply of 5 to 35 volts DC. It allows the microphone 21 to have the same volume as the standard microphone designed to be used with each radio. The thin metallic sheath 52 encapsulating or covering the impedance matching circuit 50, with the exception of the opening 53, is approximately 1/32 to 1/16 inches thick. This covering in lead substantially reduces noise interference. 
     The flexible cable 33 used to position the earphones 31 in the helmet 12 in juxtaposition with the wearer&#39;s ears are black vinyl-covered flex arms from UNIPRISE International, Inc. of Terryville, Conn. The flex cable 33 used was 0.315 inches in diameter and about 3 feet in length. The actual length used is, of course, dependent on the helmet 12 size and placement of the flex cable 33 in the helmet 12. 
     Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. it is, therefore, to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.