US2813933A - Hearing aid - Google Patents

Description

E) M. WILUAMS 2,813,933

HEARING AID Nov. 19, 1957 Filed May 26, 1953 2 Sheets-Sheet 1 lNvENToR EVERARD MWILLIAMS Nov. 19, 1957 E. M. WILLIAMS 2,813,933

' HEARING AID Filed May 2e, 1953 2 Sheets-sheet INVENTOR EVERARD M. WILLIAMS @if www Patented Nov. i9, i957 HEARING Aro Everard Mt Williams,.Pittsburgir, Pa., assigner to Alan M; Sfcaife, PittsburghmPa.

Application-Win26, 1953, Serial No. 357,556

3 Claims. (Cl. 179-107) This` invention.relatestohearingaids and is in the nature of an improvement ,over` the invention of vUnited States Patent No. 2,613,282. In that patent there is disclosed a hearing vaid characterized byits inconspicuousness and lcompactness shown as .being contained within a support having. the general conguration of aspectacle frame. In. that hearing aid thesoundvibration receiving portion is disposedin the bridge of the spectacle frame. A" soundreproducer is carried by the support near the ear of the user and means are provided Wherebysound vibrations ,received bly the` sound vibration receiving portion are convertedinto audible sounds in the sound reproducer, the hearing aid being conned .entirely within the support and having no exterior Wires, ear plug or connections offany kind.`

The hearing aid of" said patent is` satisfactory` but requires'thebridge portionv of thesupportto be undesirably large "and also has limitations as to capacityl and` life because all of the operatingparts must be conned within very smallfspaces.

I providel a hearing aidfin which I`utilize. a `iirstunit wornV upon they users bodyV converting sound vibrations into electric Yand -magnetic eld 'oscillations together with.

a second unit physically entirely separate from and unconnected with the rst unit Worn upon the users head. receiving oscillations from the first unitan'd converting the same into audible sounds adjacent theusers ear.

It has previously beenproposed to provide a hearing .aid having two separateunits, one carried bythe user upon his torso andthe other constituting an ear; plug Without'co-nnecting Wires, the usersbody being relied upon as a portion ofthe conducting circuit rendering the device operable. This requires that there be two body electrodes in firm contact with the `body of the user, one at the torso and .the other at the ear. Sucha hearing aid is unsatisfactory, iirst, because of the necessity'ofthe provision of the b'ody electrodes and, second, because the ear plug is unsightly and makes known the fact that the user is hard of'hearing. Special clothing must be provided to enable application ofthefbody electrode to the torso of the user While the microphone is disposed outside the clothing.

My hearing aiddoes not employ the body of the user as a portion Otan electrical circuit necessary to operation of the hearing aid .and hence krequires-no body electrodes and no special clothing, and r alsorrny hearing aid dispenses with an ear plug: It has all `ofthe advantages of the hearing-aid ofPatentNo. 2,613,282 yand the additional advantages: that ay smaller andless conspicuous bridge portion may be provided in the support which has the general configuration ofra spectacle frame and'that a much-'more powerfulrunit for receivingand converting sound vibrations maybe employed since that unit visvvorn uponv the` usersbody below ythe .head 'and hence may be of substantial rsize.y Such `unit maybe concealed'fbeneath theV outerV clothing tof :the ruser; `andlit` may befcompletely outof contactwith the` usersfbody. Actually such unit may. be .-of considerablysmaller size Lthan ay conventional t hearingfaid which is; Worn upon the users body and connected by Wires with an ear plug or bone conducting unitzcarried .by a headclamp.

. My hearing aid'may take different forms, one form 5 comprising-means Worn upon the users body converting sound vibrations into an-oscillating-electricfield and means physically entirely separate from and unconnected Withtherst mentioned means Worn upon the users head v.intersecting the electric iield created by the iirst l() mentioned means and converting the electrical oscillations. induced in its conductors hy this field to audible soundsadjacent' the users ear, and another form comprising means Worn upon the users body converting sound vibrations into, an oscillating magnetic eld and meansk physicallyy entirely separate from and unconnected with the first mentioned means Worn upon the users head intersectingmagnetic. flux in said eld and converting electrical oscillationsinduced in its conductors by this field lations that 'they are. not reliedupon for operation of thek hearing aid although they might beso employed.

' The sound converting means of my hearing, aidmay include: a conductor Worn at least partially about the users neck., the conductor need not extend completely about the users neck but should have portions extending at least` to" the sides of the neck. When the magnetic field is utilized-the conductor should extend completely .about the users neck. I find, it convenient to disposev the con- 40 ductor in a necktie. The conductor may take Various forms, one4 preferred form being a braid of Phosphor 'bronze which has the desired electrical properties and is very'lexible so that it maybe deformed and knotted with the lnecktie.` downwardly from theI neck is connected With a microphone uni-t. The microphone unit may be Worn upon the clothingof the user completely out of contact with the users-body.

-Sound vibrations are converted into electric and magnetic iield osciliations in the conductor which extends at least `partially about the users neck and those oscillations *iny turn produce in conductors in the temples of the support worn on the users head a current of electricity Which isfconverted into audible sounds adjacent the users ear. The conductors in the temples of the support intersect the electricorimagnetic iield emanating from `the conductor Whichisdi'sposed at least partially about the users neck whereby a current flow is induced in the former.

Other details, objects and advantages of the invention @Q will: become apparent as thefollowing description of certain present preferred embodiments thereof proceeds. l In theaccompanying drawings I have shown certain presentpreferred embodiments of the invention in which: Figure 1 is an electrical diagram or one form of the unitof Vthe hearing aid which is adapted to be Worn upon the users body;

Figure 2'is asomewhat diagrammatic illustration of onerform of the unit of the hea-ring aid which is adapted p Indeed, electromagnetic waves of.

When the .oscillating electric field is utilized The end of the conductor extending' Figure 4 is an electrical diagram of the hearing aid unit shown in Figures 2 and 3;

Figures 5 and 6 are diagrams illustrating the operation of the form of hearing aid shown in Figures l4; and

Figure 7 is a diagram illustrating the operation of another form of my hearing aid.

The means for converting sound vibrations into electric and magnetic field oscillations which is worn upon the users body is illustrated diagrammatically in Fig. 1. In that figure there is shown a microphone 2, an audio amplifier 3, an audio modulator 4, an oscillator 5 and a conductor designated generally by reference numeral 6. The microphone 2, the audio amplifier 3, the audio modulator 4 and the oscillator 5 may be connected in conventional manner as well known to those skilled in the art and may be disposed within a small and inconspicuous case. The conductor 6 extends from the oscillator out of the case as shown in Figure 1 and has two branches 7 and 8 extending alongside the users neck at opposite sides thereof. The branches 7 and 8 may be connected together at the rear of the users neck forming a complete loop if the magnetic field is to be utilized for operation of the hearing aid. If the electric field is to be utilized it is not necessary that the branches 7 and 8 be joined together at the rear of the users neck, those branches having the desired function because they are respectively generally below and parallel to the conductors in the temples of the support worn on the users head as will presently be described.

I find it most practical to incorporate the conductor 6 in a necktie and to make the conductor continuous lengthwise of the necktie. While, as indicated above, a continuous conductor capable of forming a closed loop is required when the magnetic field is to be utilized a1- though not required when the electric eld is to be utilized, such a continuous conductor may be employed in either case. I desirably dispose a Phosphor bronze braid inside the necktie and after the necktie has been tied I connect together the ends of the braid at the ends of the necktie and connect the same to the oscillator. Sound impinging on the microphone 2 causes weak audio frequency currents which are amplified by the audio amplifier and fed to the audio modulator which modulates the high-frequency carrier produced by the oscillator. Modulated carrier currents are fed to the conductor 6.

The portion or unit of the hearing aid which is worn upon the users head and which has the general configuration of a spectacle frame is shown in Figures 2 and 3. The support is designated generally by reference numeral 9 and as shown in Figures 2 and 3 has the general conguration of a spectacle frame. It has spaced apart bearing portions 10 adapted to bear on the nose of the user. It has opposed temples 11 and 12 extending to positions adjacent the ears of the user and having slightly curved end portions 13 and 14 respectively which are adapted to lie atop the ears and press against the users head, as against the mastoid bone, and to cooperate with the portions lll to maintain the support in position on the head. The portions 10 are integral or connected with a front part 15 of the support 9. The front part 15 has two portions 16 shaped as lens frames connected by a bridge 17. When the portions 10 bear on the users nose the bridge 17 is disposed at the front of the upper portion of the nose as is conventional.

The sound reproducer is disposed in the curved end portion 14 of the temple 12 of the support 9 and is shown diagrammatically at 18 in Figure 2. The sound reproducer 18 is of the bone conduction type and is by the temple 12 of the support pressed against the mastoid bone generally above the users left ear. The sound reproducer is suitably mounted in the portion 14 so that when it is activated it will in turn through the mastoid bone of the user activate the auditory nerve of the user or in other words produce audible sounds adjacent the vusers ear. The principle of operation of the bone conduction type sound reproducer 18 is the same as the principle of operation of any bone conduction type sound reproducer but the sound reproducer is rendered inconspicuous or, indeed, invisible by disposing it within the support.

The power unit for the portion of the hearing aid carried by the support 9 is disposed within the temple 11 of the support and may comprise two batteries 19 and 20 electrically connected as will presently be described. The batteries are of appropriate capacities, the battery 19 desii-ably having a voltage of the order of 3 volts and the battery 20 desirably having a voltage of the order of 30 volts. The function of the power unit consisting of the batteries 19 and 20 is to supply the necessary electrical energy to operate the portion of the hearing aid carried by the support 9.

The support 9 carries, desirably in the bridge 17, a detector designated diagrammatically by reference numeral 21 in Figures 2 and 3 and which will be described in detail below. The detector may be quite small and completely concealed within a normal sized spectacle bridge, obviating the necessity of providing an abnormal and unsightly bridge of large size containing a microphone as in United States Patent No. 2,613,282.

Three transistors 22, 23 and 24 and two transformers 25 and 26 may be disposed within the temple 12 as shown in Figure 2. A switch 27 for closing and opening the electrical circuit is provided in the temple 11, the switch comprising a turnable ring operable by the fingers of the user, the circuit being closed when the ring is in one rotative position and being open when the ring is in another rotative position. A similar ring 28 is provided in the temple 12 for volume control. The required conductors are not shown in Figures 2 and 3 but are disposed within the support 9. Preferably the support is hermetically sealed; at least the transistors should be hermetically sealed to exclude moisture.

The portion of the hearing aid Worn upon the users head is, in general, like that shown in United States Patent No. 2,613,282 and reference is made to that patent for details of construction which do not constitute the present invention.

One electrical circuit which may be employed in the portion 0f the hearing aid worn upon the users head is shown in Figure 4. The detector unit 21 comprises a resistance unit 29, a capacitance unit 30 in parallel with the resistance unit 29 and a rectifier 31 connected as shown in Figure 4. The voltage is fed by way of chokes 32 and 33 to conductors 34 and 35, respectively. A choke 36 is also provided to constitute a return path of direct current components passing through the detector.

The conductor 35 extends to the emitter electrode 37 of the transistor 22. A conductor 38 extends from the collector electrode 39 of the transistor 22 to one side of the transformer 25. The circuit through that side of the transformer 25 is completed by a conductor 40 which extends to a conductor 41 which extends to the switch 27 and a corresponding conductor 42 which extends from the switch 27 to the battery 20. The batteries 20 and 19 are connected in series by a conductor 43.

The 4Opposite side of the transformer 25 is connected through a conductor 44 with a contact member 45 operated by the ring 28 cooperating with a resistance pad 46. A conductor 47 from the resistance pad 46 is connected to the transformer 25 at 48. The 'conductor 47 is connected with the conductor 34 which extends to the switch 27. A conductor 49 extends from the switch 27 to the battery 19.

The transformer 25 is connected with the emitter electrode 50 of the transistor 23 by a conductor 51. The collector electrode 52 of the transistor 23 is connected with the transformer 26 by a conductor 53. A conductor 54 leads from the transformer 26 to the conductor 41.

The transformer 26 is connected with the emitter electrode 5S of the transistor 24 by a conductor 56. The collector electrode 57 of the transistor 24 is connected agei'agaa with the soundreproducerlA by acoductor 5S. conductor"59"leadsfrom the-soundreproducer 18 toithe'conductor 41. 1

l "The ground electrode-60 ofthe transistor 22, 'thefground electrode -61 `of the transistor323'rlandfthe groundelectrode 62*ff`the 4transistor Y24--are grounded, A ask is thef conductor 43. A ground conductor may connect the ground electrodes 60, 61 and 62 and the conductor 43.

The unit worn on the users head serves to pick up a high frequency voltage from the branches 7 and 8 of the conductor 6. A voltage is developed in the detector 21 by reason of the electric field coupling between the branches 7 and 8 -of the conductor 6 and conductors 63 and 64 disposed within and extending lengthwise of the temples 11 and 12, respectively. The detector demodulates the high frequency signal and delivers an audiblefrequency voltage output to conductors 321/2 and 331/2. Such audio-frequency voltage is conducted through conductor 35 to the emitter electrode 37 of the transistor 22. Changes in current between the emitter electrode 37 and the ground electrode 60 of the transistor 22 produce changes in current in the transistor path between collector electrode 39 and ground electrode 60 which by virtue of the relatively high voltage of the battery have energy greater than that exerted by the current in the conductor 35, emitter electrode 37 and ground electrode 60. Transformer reduces the voltage of the amplified speech currents from transistor 22 to match the resistance of the circuit between the emitter electrode and ground electrode 61 of transistor 23. The resistance pad 46 acts in the nature of a rheostat to vary the amplitude of the electrical vibrations reaching transistor 23 in order to control the volume of current employed for operating the hearing aid and hence the loudness of the sounds emanating from the sound reproducer 18. The energy of the electrical impulses originating in the path between the collector electrode 52 and the ground electrode 61 of the transistor 23 derived from the battery 20 is fed to the sound transformer 26 which matches the impedance between the output of the transistor 23 and the input of the transistor 24 in a manner well known in the art. The output of transistor 24 derived from the circuit including collector electrode 57, sound reproduc-er 18, battery 20 and ground electrode 62 represents impulses originating in detector 21 so that the users auditory nerve is activated.

I shall now explain how voltage is developed in the detector 21. This will be done with reference to Figure 5 which is a diagram showing the relationship between the units carried upon the users body and carried upon the users head, respectively, and with reference to Figure 6 which is an equivalent electrical circuit diagram.

Stray capacitances are inherent between the branches 7 and 8 of the conductor 6 and the respective conductors 63 and 64. The outer end of the conductor 63 is designated a and the outer end of the conductor 64 is designated b. The inner end of the conductor 64 is designated c and the inner end of the conductor 63 is designated d. These same letters are uniformly applied in all of Figures 4, 5 and 6. The outer end of the branch 7 is designated a and the outer end of the branch 8 is designated b. The inner end of the branch 8 is designated c and the inner end of the branch 7 is designated d. The stray capacitances are designated symbolically in Figure 5 as follows: 65 between a and a; 66 between b and b; 67 between c and c; and 68 between d and d'.

Figure 6 shows in addition to the stray capacitances above mentioned the self-inductances of the conductors as follows: the self-inductance 69 of the conductor 63; the self-inductance 70 of the conductor 64; the self-inductance 71 of the branch 8 of the conductor 6; and the self-inductance 72 of the branch 7 of the conductor 6. The source of voltage in the conductor 6 is indicated' diagrammatically in Figure 6 at 73. The voltage across source 73 tends to cause current to flow from c to C,

throughfdetector'iZl toit and back via d to $73. `r`l`his `fp`a`th has a"1"elatively"hi'gh impedancel to current and the result is a very small voltage across detector 21. The voltage across source 73,also.tends to cause current to ow from Yc"'tl1rou`gh inductance`71' to bl and thence from b through straycapacitancef-66to b,?thence via inductance 70-tovc,throu gh detector 21 tod, thence via\inductance 69 to a, thence via stray capacitance 65 to a' and thence via inductance 72 to d and back to 73. The reactances of the inductances and stray capacitances are opposed in accordance with well known properties of these circuit elements so that the second mentioned path of current fiow has a lower impedance, resulting in fairly large voltages across detector 21. This high frequency amplitudemodulated voltage is detected by the combination of resistance 29, capacitance 30 and rectifier 31 (Fig. 4) so that an audio-frequency voltage and steady direct current component appear across points 74 and 75. This voltage is fed by way of chokes 32 and 33 to the amplifier. These chokes serve to keep undesired high-frequency voltages induced in the amplifier leads in a manner similar to the voltages described above from interfering with the operation of the amplifier. Choke 36 serves to provide a return path for direct current components passing through the detector.

Figure 7 is a diagram illustrating the operation of a hearing aid in which a magnetic field is relied upon for operation. In Figure 7 the branches 7 and 8 of the conductor-.6 are connected together behind the users neck as shown at 76. The unit carried upon the users head operates as a closed circuit consisting of inductance 69, detector 21, inductance 70 and stray capacitance 77 behind the users head. Current flows in the loop 73--7-76- 8-73 due to the voltage at 73. Such current flow causes the setting up of a magnetic field which is intersected or pierced by the conductors 63 and 64; in other words, lines of magnetic flux from the magnetic field link the circuit of the unit worn upon the users head. Voltages are induced in that circuit and appear at the detector 21.

While I have shown and described certain present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied Within the scope of the following claims.

I claim:

l. A hearing aid comprising means worn upon the clothing of the user completely out of electrical contact with the users body, said means converting sound vibrations into electric and magnetic field oscillations, and means physically entirely separate from and unconnected with the first mentioned means mounted in a support having the general configuration of a spccacle frame Worn upon the users head receiving oscillations from the first mentioned means and converting the same into audible sounds adjacent the users ear.

2. A hearing aid comprising means worn upon the clothing of the user completely out of electrical contact with the users body, said means converting sound vibrations into electric and magnetic field oscillations, and means physically entirely separate from and unconnected with the first mentioned means comprising a support having the general configuration of a spectacle frame worn upon the users head and mechanism therein, said second mentioned means receiving oscillations from the first mentioned means and converting the same into audible sounds adjacent the users ear.

3. A hearing aid comprising means including a conductor worn at least partially about the users neck completely out of electrical contact with the users body, said means converting sound vibrations into electric and magnetic field oscillations, and means physically entirely separate from and unconnected with the first mentioned means mounted in a support having the general configuration of a spectacle frame worn upon the users head re- Cal'.

References Cited in the le of this patent UNITED STATES PATENTS Eichorn Nov. 12, 1929 Perlman May 18, 1943 Rosenberg -n July 12, 1949 Halstead Sept. 11, 1951 Potter r Sept. 25, 1951 Hathaway et a1. Oct. 30, 1951 Scaife Oct. 7, 1952

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