US2123119A - Hearing and apparatus - Google Patents

Description

Jul -5, 938.- W PENN 2,123,119

HEARING AID APPARATUS Filed June 26, 1936 A- V/9\0UTPUT g 70 I Penn mutant- ,1938") Y z,1z3,119

UNITED STATES 'PATENTfoi-rica 1 $5.31??? $113121) T? 'i V This invention relates to a new and'improved flieted, and may be adjusted. and altered from p mtus used in aidinghearing and more partime to time to suit. the needs of the user, as his v ticularly toa method and device for obtaining a needs may change.

J frequency selective amplifier for use in aiding This is accomplished by providing a trans- 5 hearing of the partially deaf. An object of this former or electromagnetic; device, having one or 5 invention is to provide anapparatus that may more secondary windings to which are coupled v be used-in aiding hearing and which is adapted. devices'which select the frequencies or bands of to amplify selected frequencies. frequencies which aregto be attenuated. B y al- Another object of this invention is to provide tering or ch e ra risti of these a hearing aid apparatus in which the frequency latter devices, the frequencies or bands of fre- '10 response characteristic may be controlled by quenciesto be att n fl are an Where means of an electromagnetic device, such asa it is desired to change Only O q e cy band transformer or a choke coil, the frequency charwhich is to be attenuated, this may likewise be acteristics of which may be'controlled or adjusted. one t eq al a l ty.

13' Still another object of this. invention is to Further'details of this invention warm ap- 15 provide a hearing aid apparatus with an electroparent tqihose skilled in the art to which it magnetic device which. is'adapted to controlthe relates, from the following specification and the frequency response of said apparatus and which drawing, in which, briefly, Figure 1 illustrates an is adapted to attenuate certain predetermined embodiment ofthisinventionfFigures 2 and 2a 3 selected audio frequencies depending upon the. illustrateanother embodiment of this invention hearing deficiencies of the partially deaf user. and Figure} shows an electrical network em- A further object of this invention is to provide ployed for the purpose of explaining the operahearing aid amplifying apparatus adap'tedto -attion of this invention. l l tenuate certain selected audio frequencies or Referring to Fig 1 of the drawing n il. I

b d audio frequencie depending n t .,reference numeral lildesignates a sound pick-up 25 hearing deficiencies of the hard of hearing or .1 (ital/ice micmphoner Sound recmd partiallydeaf user. reproducing device, and the like, connected to j Still a further object of this invention is to 1 e p ma of a ans rme f a d to a providq hearing i device adapted t used suitable source of current supply H. Thesec by pe'rs'qns gflflcted th partial d f said ondary ii of the transformer is connected to 80 hearing aid device employing an electromagnetic .thegrid electr de' t th l tric discharge dev lapparatus having a plurality of windings, each I! and to a C battery'lB which is connected to of said windings being'adapted to function to the cathode of the electric discharge device. A a attenuatecertain frequencies or bands of fresuitable'sourcejofcurrent supply 11 is provided I quenciegito which th hard of hearing" user 1s for energizing the anode of the electric discharge the most sensitive. 3 device amplifier 15. The anode of the device I Other and further objects of this invention ll-is connected to the impedance winding l8 will be apparent to thoseskilled in the art to wlileh'isshunted across the output terminals l9 4a which it relates from the following specification of the amplifier. -'I'iie impedancifl is provided 40 u .and theclaims." I "with two additional circuits coupled to' thecore' r In accordance iwith thisinvention I provide a thereof forthe purpose of altering the frequency circuit arrangement adapted to be used in hearcharacteristic of this'impedance device. These ,ing aid apparatus, employing an electromagnetic "additional windings are designated as 20 and 2| 4 ,device, such as a transformer, in which one or and they may be wound xon the core 22 of the more windings are employed to attenuate one impedance device "in various ways depending or more frequenciesgor bands of frequencies the upon theresults desired. '{Ihese' windings 20 and ..level of which it is desired to reduce. V -2i may be wound over the winding I8 so as to 'I 'he :apparatusof my inve tion is simple in' be concentrictherewith and maybe movable with #0 construction and may beeasil and readily made respect to the winding It in, order to he posi- 5 i to fulfil the needs of persons aiiiictedwith partioned over different sections'of-the latter windtial deafness. The apparatus-of my invention i'ngr The-terminals of the windings 20 and-2| maybe made to attenuate certain frequencies are connected tojsuitable impedances 24 and or bands-of frequencies, dependingupon the narespectively. The. .nature,.--of these impedances 65- ture of the deafness with which the user is at will govern the effective impedance between the v mutual impedance thereto, the response frequency characteristic of the hearing aid apparatusof this invention can be controlled as desired. Where convenient and desirable to obtain further variation in 'the frequency response characteristic, an additional impedance or impedancesmay be connected to the taps Ila and Ilb of the impedance II, or the output circuit directly.

In the circuit diagram shown in Figure 1 the may be connected to these taps anode current of the electric dischargedevice.

amplifier ll obtained from the source of. current supply I! passes through the winding It or through this winding. and the output device connected to the terminals it, This current may be prevented from flowing through the impedance winding II by connecting resistance across this winding between the source of current supply I! and the anode of the device I 5 and by inserting a suitable blocking condenser between this resistance and one of the terminals of the winding II. This will prevent the anode current derived from the source I! from passing through the winding I I in cases where it is decurrent from magsired to prevent this anode netizing the core of this impedance device. q

The windings II and II may be wound each with a different number of turns or each with a different inductance. Each of these windings may be tuned by means of suitable condensers to be resonant to certain audio frequencies and to absorb power at said frequencies from the circuit of the winding ll. Thus the frequency characteristic of the hearing aid device may be varied, d pending upon the characteristics of the impedance device. Furthermore the resonance characteristics ofthe circuits of the windings II and Il may be broadened if desired in one or both of these windings to cover a relatively broad band of frequencies, by connecting a resistance of suitable size in series with each of these windings.

In Figures 2 and 2a I have shown the impedance winding I. connected between the microphone or other soimd pick-up device and a reproducing device 28,

tric discharge device amplifier.

winding II or by moving thecorell, to obtain the desired frequency response characteristic.

The operation of the he'aringaid 'ofthis invention. in cases where the windings I, II, and II oi the impedance device are closely coupled may be determined from the following when considered with the equivalent electrical network shown in Figure 3.

l'br the general'case of a transformer with a between primary and secondary windings the without theuse of an elec- The operation impedance looking into the primary winding of the device is Z 21X, is= i+ Z.+J(XI F)=RI+ In the above equation:

Ri=l=tesistance of primary winding.

Ri=Resistance of secondary circuit including resistance component of load.

X1=Reactance of primary winding.

X:=Reactance of secondary winding.

X=Total reactance of secondary circuit.

The equation shows that for any given coefficient of coupling k the impedance looking into the, primary is a function of the load impedance connected to the secondary. The impedance Z1:

. here corresponds to the impedance designated as Z; in the case of the closely coupled transformer.

For a closely coupled transformer, Z1 is equal to the quantity 1n divided by n: squared, times Z2. Where m is the number of turns in the primary of the device It and m is the number of turns in the secondary of this device. Z: is

' the impedance in ohms of the impedance device connected to the aforesaid secondary. If Z2 is a pure resistance then the effect of connecting it across the winding 1:: is in effect the same as shunting the output device of impedance Zr with a resistance. If Z: is an inductance 1-, for example, the eflect of connecting it across the winding m is the same as shunting 2;- with an. inductance equal to the quantity m divided by m squared, times n. On the other hand, if Z: is a condenser the eifect of connecting it across the winding m is the same as shunting Zr with a condenser equal to the quantity as divided by 1&1 squared, times 0, c being the value of the condenser. If the transformer has more than two windings the impedance looking into any winding, called for convenience the primary winding, of a transformer having N windings is equal to the self-impedance Z, of the primary winding multiplied by the product of all the load impedances Zs, Zs, Zs, Zn to which the other or secondary windings are connected, and divided by the sum of the products of the various self impedances of the secondary windings Z2,

' Zs, Z4.-Za and the various load impedances with the self impedance of impedance pedance of winding ll, ,of winding ll, Z: is winding II, and Z. and

Marge 3 55's. Ess

impedance Zs, the power loss introduced into the circuit by the effective shunt impedance Z5 may be determined from the following equation which gives the power loss in decibels.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. A device foraiding hearing by attenuating frequencies to which a user of the device is normally sensitive, comprising aninput device, an output device. an electromagnetic frequency attenuating device having a winding shunted across said output device and eletromagnetic means for altering the frequency attenuating characteristics of said frequency attenuating device, said last mentioned means including one or more impedance circuits coupled to. said fre-,

quency attenuating device for the purpose of introducing losses equal toin decibels, where 2,; is the effective impedance in the circuit of said input device, Zr is the impedance of said output device and Z5 is the effective shunt impedance of said frequency attenuating device, said losses being introduced at frequencies determined by the characteristics of said attenuating device for reducing the response of the hearing aid at these predetermined fre-' quencies to which the user is normally sensitive to a level substantially below the normal response of the hearing aid the remaining frequenciea:

2. A device for aiding hearing by attenuating frequencies to which a user of the device is'normally sensitive, comprising: a. sound pick-up and translating device, a vacuum tube amplifier having an input and an output circuit, means for connecting saidsound pick-up and translating device to said amplifier input circuit, a sound reproducing device connected to said amplifier output circuit, a frequency selective attenuating device comprising a main winding connected across said reproducing device, said frequency attenuating device having at least two auxiliary windings coupled together, an impedance device connected to each of said auxiliary windings for altering the frequency characteristics of said attenuatingdevice, said impedance devices connected to' said auxiliary windings of said attenuating device being adjusted so that said attenuating device will absorb power from the circuit of said amplifier and' fr'om said sound reproducing device at frequencies determined by the characteristics of said impedance devices and said windings for the purpose of reducing the response of the hearing aid at these predetermined frequencies, to which the user is normally sensitive, to a level substantially below the normal response of the hearing aid to the remaining frequencies. w

3. A device for aiding hearing by attenuating frequencies to which a user of the device is nor-- mally sensitive, comprising: a sound pick-up and translating device, a' vacuum tube amplifier having an input circuit and an output circuit, means for connecting said sound pick-up and translating device to said amplifier input circuit, a sound reproducing device connectedto said output circuit, a frequency attenuating device having a main winding connected across said sound reproducing device and a pair of auxiliary windings coupled to said main winding, an impedance'device connected to each of said auxiliary windings,

each of said impedance devices forming a power' absorbing circuit with the auxiliary winding connected thereto, having predetermined frequency characteristics such that the hearing aid device may be adjusted to meet the deficiencies of partially deaf persons by selecting impedancedevices of such frequency characteristics thataudio frequencies to which the partial] deaf person is normally sensitivewill be at enuated when the selected impedance devicesareconnectedto'said auxiliarfwindings.

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