US 3210723 A
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Oct. 5, 1965 MARTELLI ETAL 3,210,723
ELECTRONIC SELF-CONTAINED APPARATUS FOR SOUND OR VOICE COMMUNICATION 2 Sheets-Sheet 1 Filed April 6, 1962 w w m Luigi Morrelli 8 Carlos Reinberg by M oxwe E. Sparrow ATTORNEY 1965 MARTELLl ETAL 3,210,723
ELECTRONIC SELF-CONTAINED APPARATUS FOR SOUND OR VOICE COMMUNICATION Flled Aprll 6, 1962 2 Sheets-Sheet 2 Sensitive Stationary Microphone Cup FIG.4
VIII/170111111 t 1 r a I Z r 5 i I 4 Magneto -Electric or Electrodynamic Pilot Unit Second Low- Frequency Low- Power Amplifier Low-Frequency High-Power Amplifier Electric Batteries FlG.3
/Nl E /V7'0R$. Luigi Martelh 8\ Carlos Reinberg y Maxwell E. Sparrow ATTORNEY United States Patent 3,210,723 ELECTRONIC SELF-CONTAINED APPARATUS FOR SOUND 0R VOICE COMMUNICATION Luigi Martelli, Via 0. Cancelliere 49/18, and Carlos Reinberg, Via Parina 28, both of Genoa, Italy Filed Apr. 6, 1962, Ser. No. 185,674 Claims priority, application Italy, Apr. 10, 1961, Patent 647,081 3 Claims. (Cl. 3405) This invention relates to an electronic self-contained apparatus for underwater sound or voice communication, or between the latter and the aerial medium, or vice-versa.
In the field of underwater communications, many systems are known which are based upon the emission of modulated waves, either electromagnetic, supersonic or sound waves, which are received by special devices which are adapted to detect them and to render them audible. All these systems make it necessary for the immersed listening person to be provided with a suitable individual receiver. It is known that the presently marketed devices of this kind are of a rather complicated nature and, therefore, are impractical and expensive, so that they may be used only in exceptional cases. Moreover, they may be used only in conjunction with a particular breathing apparatus or breathing self-contained apparatus. A study has been undertaken to obviate these drawbacks, from the economic, practical and functional points of view. The present invention is the result of this study. The apparatus according to the invention, which is based upon acoustical, electrical and electronic principles, enables a person being immersed in a liquid medium and provided with any breathing apparatus to speak freely and to transmit his voice directly through the liquid medium, also enhancing his sense of hearing, while permitting his normal breathing, thus providing an intelligence wireless communication system between immersed persons or between the latter and other persons afloat or ashore, or vice-versa.
The apparatus according to the present invention comprises a particular universal mouthpiece permitting an excellent breathing and a perfect pronounciation, while a minimum-sized throat microphone, which engages the cutaneous surface of the neck near the throat, detects the vibrations of the latter and conveys them to a first lowfrequency high-power electronic amplifier circuit, enclosed in a sealed housing, which energizes an acoustical transducer which is adapted to transmit sound spherically through the liquid medium. A portion of such a transducer is designed to receive sounds in the liquid medium and to transduce them to a second separate amplifier circuit having less power than the first one and which energizes two earphones so as to permit better hearing. This is efiected by virtue of the physical phenomenon of the passage of sound waves through three mediums having different acoustical resistances. In accordance with this principle, such energy is totally transferred from one medium to another one having a different acoustical resistance if the matter filling the interspace between said two mediums has a thickness which is either A (one fourth) of the vibration wavelength of said matter or an odd multiple thereof, and if the acoustical resistance thereof is the square root of the product of the two acoustical resistances of the adjacent mediums. This may be explained in more detail as follows. The matter filling the interspace between the two adjacent mediums is a natural or artificial polymer material, preferably rubber, which has the desired properties of creating the natural phenonenon consisting in the passage of the sound vibrations between the three mediums of dilferent acoustical resist ance. The interposed medium is formed like an envelope, as it will be described in more detail, the walls 3,216,723 Patented Get. 5, 1965 of which have varying thicknesses in order to obtain a non-uniform outer surface which is exposed to the liquid medium. These variations in thickness do not permit the total sound passage without losses of energy between water and air of a single frequency or wave length, but rather transmits the entire spectrum of freqeuncies and wave lengths of which the sounds of the human voice are composed, depending on the dimensions of said thickness. 1
By virtue of this phenomenon, the output of the apparatus according to the present invention is so high as to enable the use of such an apparatus for all underwater communications in a range within the presently possible diving depth, so such to permit individual direct hearing without any intermediate means. In order to improve this hearing a particular sound receiving system is provided which forms a part of this assembly.
Inasmuch as the apparatus according to the present invention can be easily constructed in mass production, the cost thereof can be so reduced as to permit the widest application thereof, both in the industrial and sport fields.
A preferred embodiment of this invention is shown, as a non-limitative example, in the accompanying drawings, wherein:
FIG. 1 is a horizontal sectional view of the mouthpiece, on line AA of FIG. 2;
FIG. 2 is a front view of said mouthpiece;
FIG. 3 is a diagrammatic axial section of the assembly comprising the electronic device and the transducer;
FIG. 4 shows the throat microphone in a smaller scale;
FIG. 5 shows the earphones in a smaller scale.
As clearly shown in FIGS. 1 and 2, the mouthpiece designed for this apparatus, but usable separately for breathing when being immersed-is provided with a tubular projection 1 which can be used for connection to any vital gas dispenser. The base of this projection merges into a concave portion 2 extending in the same direction as the lips and having a sufiicient thickness to prevent any distortion thereof due to a pressure diiferential or to a mechanical stress. The mouthpiece is provided with an inside thin rim 3 which ensures a tight matching even during movement of the mouth, which movement can be normally effected by virtue of said concave portion 2. This is an essential feature for the correct operation of the apparatus, since it permits one to speak freely. The mouthpiece is also provided with two internal projections 4 for being held by the teeth in such a manner as to permit a free movement of the tongue. The mouthpiece is properly secured to the user by means of a strap 5. The mouthpiece is made of a natural or artificial polymeric material having suitable resiliency.
Sound vibrations-produced by the perfect unhindered talking which is permitted by the particular features of the mouthpieceare transduced through a throat microphone 6 which is adapted to engage, merely by pressure contact, the cutaneous area of the neck near the throat. This throat microphone 6 is of the known conventional type for operating when immersed in a liquid, at considerable depth. The connecting line is sealingly connected both to the device 6 and to the junction of the body 7 of the apparatus.
Within said body is a tightly sealed first low-frequency high-power electronic amplifier circuit 8, which is completely transistorized and ensures a hgih amplification gain. The weak phonic currents from the throat microphone 6 are led to the input of circuit 8 in order to be amplified sufficiently to produce the energy which is necessary to properly operate the transducer for liquids, which is formed by components 9, 10, 11 and 12. Component 9 is either a magneto-dynamic or electro-dynamic pilot unit, depending upon the circuit characterisctics, having a pressure chamber which is adapted to transduce sound vibrations into a gaseous medium. This pilot unit consists of a conventional, commercially obtainable classic magneto-dynamic or electrodynamic device combined with a sound box commonly used for controlling loudspeakers with horns. This gaseous medium is enclosed in the pilot unit 9 and in the acoustical radiating element 11. The element 11 has an inverted shape so such to be of reduced length while assuring the desired increase in the sound-radiating area, which area is located in front of the exit of the pilot unit 9. Waves emitted from this unit move axially through the tubular member 11a and upon coming out from the latter are reflected along an opposite direction so as to move, externally of member 11a, across a particularly shaped area of element 11. At the end of this area, waves are again reflected against the outer sloping surface of element 11, which thus effects a final radial reflection.
A cup-shaped housing 10 is mounted around the acoustic radiating element 11 and is sealingly connected to the body '7. The housing 10 is made of natural or artificial polymeric material such as rubber which, being unable to Withstand a strong external pressure (such as the liquid pressure) is provided with an internal tubular backing member 12 having a thoroughly slotted wall. This member could be also substituted by any other suitable mechanical or pneumatic means.
In order to achieve the proper conditions for the occurrence of the acoustical phenomenon of total transfer of sound energy through three mediums as stated at the beginning, the housing 10, besides being made of a suitable material, has a particular surface configuration whereby the walls thereof have a non-uniform thickness. This fact, in accordance with the same physical principle, allows the passage of sound waves comprised in a given frequency spectrum.
In the top of the device, on the side of the acoustic radiating element and under the bottom of the cup shaped housing 10, a recess is provided for accomodating a micro-phone cup 13. Due to said physical phenomenon, the microphone cup receives sound waves from the liquid medium and transduces them to a second low-frequency amplifier 14, having less power, which is located within body 7. An earphone transducer 15, usuable by the immersed person, is connected to the amplifier 14. This microphonic assembly plays an important part also when the apparatus is used for communication between a liquid and an aerial medium. For obtaining the communication between persons located in air and immersed in water, it is simply necessary to replace the conventional underwater transducer elements 6 and 15 by other similar conventional aerial elements. This exchange can be made by using waterproof plugs for engaging and disengaging the connecting cables of said transducer elements with the main body of the apparatus which, obviously, must be kept under water at a sufficient depth.
Circuits 8 and 14 are fed by suitable electrical batteries 16.
It is to be understood that this invention is not limited to the embodiment shown and described, and that many modifications may be made in the structure thereof without departing from the scope and basic principles of the invention. Any component of the apparatus according to the invention is adapted to be used, either individually or in combination, also in other fields or in any other way than that which has been described, and also for different purposes. This is particularly true for the mouthpiece, which might be used also on any conventional underwater breathing apparatus for delivering air or any other vital gas to the user.
What is claimed is:
1. Electronic self-contained apparatus for underwater sound or voice communications in liquid mediums as well as between the latter and aerial mediums, having a housing provided with a mouthpiece permitting both perfect breathing and perfect and natural speaking; a portable first throat microphone detecting sound or voice vibrations, a first low-frequency, high-power electronic amplifier, said first microphone conveying said vibrations to said amplifier, said first amplifier being tightly enclosed within said housing, an acoustic radiating element energizable by said first amplifier, a stationary second microphone cup located on top of said radiating element, a second low-frequency, low-power electronic amplifier receiving amplifier receiving sound waves transduced by said second microphone cup, earphones connected to said second amplifier, said housing comprising substantially a member arranged between said liquid and aerial medi-- ums, said member having substantially a thickness of onefourth or of an odd multiple of the vibration wavelength thereof, and said member having an acoustic resistance of the square root of the product of the two acoustical resistances of said liquid and aerial mediums.
2. Electronic self-contained apparatus for underwater sound or voice communications according to claim 1, and said acoustic radiating element having an inverted shape, and said apparatus comprising a pilot unit having an acoustical pressure chamber, said pilot unit being mounted in a tightly sealed enclosure, a supporting structural means, said means having a slotted Wall, said means supporting said element, and said housing enclosing said element.
3. Electronic self-contained apparatus for underwater sound or voice communications according to claim 2, and said housing consisting substantially of either a natural or of an artificial polymeric material, and having walls of a non-uniform thickness.
References Cited by the Examiner UNITED STATES PATENTS 2,638,510 5/53 Brami 1810.5 2,768,246 10/56 Klein.
2,798,902 7/57 Kursman 340-5 2,844,212 7/58 Hogan et a1. 181-18 2,937,244 5/60 Weinger l79188 3,123,680 3/64 Minton et al 3405 X 3,150,346 9/64 Polly et al. 340-5 X KATHLEEN H. CLAFFY, Primary Examiner.
CHESTER L. JUSTUS, Examiner.