Switching structures for hearing aid

A hearing aid is provided with a a programmable, signal processing circuit electrically connecting an input system to an output system, a magnetic field sensor, and a selection circuit connected to the magnetic sensor. The selection circuit may be adapted to control at least one of the input system, output system, and the signal processing circuit, where the selection circuit in conjunction with the magnetic field is configured to select the system or circuit to control based a magnetic field strength received at the magnetic field sensor being one of at least three levels of magnetic field strength.

RELATED APPLICATIONS

The present application is generally related to U.S. application Ser. No. 09/659,214, filed Sep. 11, 2000, now U.S. Pat. No. 6,760,457, and titled AUTOMATIC SWITCH FOR HEARTNG AID, which is hereby incorporated by reference.

The present application is generally related to U.S. application Ser. No. 10/243,412, filed Sep. 12, 2002, and titled SYSTEM AND METHOD FOR SELECTIVELY COUPLING HEARING AIDS TO ELECTROMAGNETIC SIGNALS, which is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates generally to hearing aids, and more particularly to switching structures and systems for a hearing aid.

BACKGROUND

Hearing aids can provide adjustable operational modes or characteristics that improve the performance of the hearing aid for a specific person or in a specific environment. Some of the operational characteristics are volume control, tone control, and selective signal input. One way to control these characteristics is by a manually engagable switch on the hearing aid. The hearing aid may include both a non-directional microphone and a directional microphone in a single hearing aid. Thus, when a person is talking to someone in a crowded room the hearing aid can be switched to the directional microphone in an attempt to directionally focus the reception of the hearing aid and prevent amplification of unwanted sounds from the surrounding environment. However, a conventional switch on the hearing aid is a switch that must be operated by hand. It can be a drawback to require manual or mechanical operation of a switch to change the input or operational characteristics of a hearing aid. Moreover, manually engaging a switch in a hearing aid that is mounted within the ear canal is difficult, and may be impossible, for people with impaired finger dexterity.

In some known hearing aids, magnetically activated switches are controlled through the use of magnetic actuators. For examples, see U.S. Pat. Nos. 5,553,152 and 5,659,621. The magnetic actuator is held adjacent the hearing aid and the magnetic switch changes the volume. However, such a hearing aid requires that a person have the magnetic actuator available when it desired to change the volume. Consequently, a person must carry an additional piece of equipment to control his/her hearing aid. Moreover, there are instances where a person may not have the magnetic actuator immediately present, for example, when in the yard or around the house.

Once the actuator is located and placed adjacent the hearing aid, this type of circuitry for changing the volume must cycle through the volume to arrive at the desired setting. Such an action takes time and adequate time may not be available to cycle through the settings to arrive at the required setting, for example, there may be insufficient time to arrive at the required volume when answering a telephone.

Some hearing aids have an input which receives the electromagnetic voice signal directly from the voice coil of a telephone instead of receiving the acoustic signal emanating from the telephone speaker. Accordingly, signal conversion steps, namely, from electromagnetic to acoustic and acoustic back to electromagnetic, are removed and a higher quality voice signal reproduction may be transmitted to the person wearing the hearing aid. It may be desirable to quickly switch the hearing aid from a microphone (acoustic) input to a coil (electromagnetic field) input when answering and talking on a telephone. However, quickly manually switching the input of the hearing aid from a microphone to a voice coil, by a manual mechanical switch or by a magnetic actuator, may be difficult for some hearing aid wearers.

SUMMARY OF THE INVENTION

Upon reading and understanding the present disclosure it is recognized that the inventive subject matter described herein satisfies the foregoing needs in the art and several other needs in the art not expressly noted herein. The following summary is provided to give the reader a brief summary which is not intended to be exhaustive or limiting and the scope of the invention is provided by the attached claims and the equivalents thereof.

One embodiment of the present invention provides a hearing aid that includes an input system, an output system, a signal processing circuit electrically connecting the input system to the output system, a magnetically actuatable switch between the input system and the signal processing circuit, and a filter connected to and controlled by the magnetically-actuatable switch. The switch allows the filter to filter a signal from the input system to the signal processing circuit or prevents the filter from filtering the signal. In an embodiment, the switch is a solid state switch. In an embodiment, the solid state switch is a giant magneto resistive (GMR) switch. In an embodiment, the solid state switch is an anisotropic magneto resistive (AMR) switch. In an embodiment, the solid state switch is a magnetic field effect transistor.

In an embodiment of the present invention, a magnetically actuatable switch is positioned between the output system and the signal processing circuit. This switch controls operation of a device before the output system or at the output system. In an embodiment, the switch selectively connects an output filter that filters the signal received by the output system. In an embodiment, the hearing aid includes a plurality of filters that are selectable based on the magnetic field sensed by the magnet switch or a magnetic field sensor.

An embodiment of the present invention provides a hearing aid that includes an input system, an output system, a programmable, signal processing circuit electrically connecting the input system to the output system, a magnetic field sensor, and a selection circuit connected to the magnetic sensor and at least one of the input system, output system and the signal processing system. The selection circuit is adapted to control the at least one of the input system, output system and the signal processing system based on a signal produced by the magnetic field sensor. The selection circuit is adapted to receive an electrical signal from the magnetic sensor and supply a programming signal to the signal processing circuit. In an embodiment, the magnetic field sensor is a full bridge circuit. In an embodiment, the magnetic field sensor is adapted to receive a pulsed power supply. In an embodiment, the selection circuit is connected to the input system and sends a control signal to the input system based on a signal received from the magnetic field sensor. In an embodiment, the input system includes a first input and a second input, and the input system activates one of the first input and the second input based on the control signal. The first input includes a microphone. The second input includes a magnetic field sensing device. The hearing aid of the present invention further includes a threshold circuit that blocks signals below a threshold value.

An embodiment of the present invention provides a hearing aid that includes a programming system that is adapted to sense a magnetic field and based on the magnetic field produce a programming signal. The programming signal, in an embodiment, includes a control sequence or code that allows the hearing aid to be programmed. The programming signal further includes a digital programming signal based on the magnetic field sensed by a magnetic field sensor.

An embodiment of the present invention includes a wireless on/off switch. The wireless on/off switch includes a magnetically operable switch. In an embodiment, the magnetically operable switch is a solid state switch. The on/off switch turns off the non-essential power to the hearing aid circuits to preserve battery power. In an embodiment, a system is provided that stores the hearing aid and provides a signal to turn off the hearing aid.

An embodiment of the invention includes a wireless switch that activates a power induction circuit in the hearing aid. The power induction circuit is adapted to receive a recharging signal from a power source and recharge the hearing aid power source. In an embodiment, the wireless switch that activates the power induction circuit also turns off the non-essential power consuming circuits of the hearing aid.

An embodiment of the invention includes a system that has a magnetic field source. In an embodiment, the magnetic field source being adapted to program the hearing aid. In an embodiment, the magnetic field source is adapted to wirelessly turn off and turn on the hearing aid. The system includes a storage receptacle for the hearing aid. In an embodiment, the magnetic field source provides a power induction signal that is adapted to recharge the hearing aid power source.

Further embodiments of the present invention will be understood from reading the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings which form a part hereof and in which are shown by way of illustration specific embodiments in which the invention can be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice and use the invention, and it is to be understood that other embodiments may be utilized and that electrical, logical, and structural changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense and the scope of the present invention is defined by the appended claims and their equivalents.

Hearing aids provide different hearing assistance functions including, but not limited to, directional and non-directional inputs, multi-source inputs, filtering and multiple output settings. Hearing aids are also provide user specific and/or left or right ear specific functions such as frequency response, volume, varying inputs and signal processing. Accordingly, a hearing aid is programmable with respect to these functions or switch between functions based on the operating environment and the user's hearing assistance needs. A hearing aid is described that includes magnetically operated switches and programming structures.

FIG. 1illustrates an in-the-ear hearing aid10that is positioned completely in the ear canal12. A telephone handset14is positioned adjacent the ear16and, more particularly, the speaker18of the handset is adjacent the pinna19of ear16. Speaker18includes an electromagnetic transducer21which includes a permanent magnet22and a voice coil23fixed to a speaker cone (not shown). Briefly, the voice coil23receives the time-varying component of the electrical voice signal and moves relative to the stationary magnet22. The speaker cone moves with coil23and creates an audio pressure wave (“acoustic signal”). It has been found that when a person wearing a hearing aid uses a telephone it is more efficient for the hearing aid10to pick up the voice signal from the magnetic field gradient produced by the voice coil23and not the acoustic signal produced by the speaker cone.

Hearing aid10has two inputs, a microphone31and a voice coil pickup32(FIG. 2). The microphone31receives acoustic signals, converts them into electrical signals and transmits same to a signal processing circuit34. The signal processing circuit34provides various signal processing functions which can include noise reduction, amplification, and tone control. The signal processing circuit34outputs an electrical signal to an output speaker36which transmits audio into the wearer's ear. The voice coil pickup32is an electromagnetic transducer, which senses the magnetic field gradient produced by movement of the telephone voice coil23and in turn produces a corresponding electrical signal which is transmitted to the signal processing circuit34. Accordingly, use of the voice coil pickup32eliminates two of the signal conversions normally necessary when a conventional hearing aid is used with a telephone, namely, the telephone handset14producing an acoustic signal and the hearing aid microphone31converting the acoustic signal to an electrical signal. It is believed that the elimination of these signal conversions improves the sound quality that a user will hear from the hearing aid.

A switching circuit40is provided to switch the hearing aid input from the microphone31, the default state, to the voice coil pickup32, the magnetic field sensing state. It is desired to automatically switch the states of the hearing aid10when the telephone handset14is adjacent the hearing aid wearer's ear. Thereby, the need for the wearer to manually switch the input state of the hearing aid when answering a telephone call and after the call is ends. Finding and changing the state of the switch on a miniaturized hearing aid can be difficult especially when the wearer is under the time constraints of a ringing telephone or if the hearing aid is an in the ear type hearing aid.

The switching circuit40of the described embodiment changes state when in the presence of the telephone handset magnet22, which produces a constant magnetic field that switches the hearing aid input from the microphone31to the voice coil pickup32. As shown inFIG. 3, the switching circuit40includes a microphone activating first switch51, here shown as a transistor that has its collector connected to the microphone ground, base connected to a hearing aid voltage source through a resistor58, and emitter connected to ground. Thus, the default state of hearing aid10is switch58being on and the microphone circuit being complete. A second switch52is also shown as a transistor that has its collector connected to the hearing aid voltage source through a resistor59, base connected to the hearing aid voltage source through resistor58, and emitter connected to ground. A voice coil activating third switch53is also shown as a transistor that has its collector connected to the voice pick up ground, base connected to the collector of switch52and through resistor59to the hearing aid voltage source, and emitter connected to ground. A magnetically activated fourth switch55has one contact connected to the base of first switch51and through resistor58to the hearing aid voltage source, and the other contact is connected to ground. Contacts of switch55are normally open.

In this default open state of switch55, switches51and52are conducting. Therefore, switch51completes the circuit connecting microphone31to the signal processing circuit34. Switch52connects resistor59to ground and draws the voltage away from the base of switch53so that switch53is open and not conducting. Accordingly, hearing aid10is operating with microphone31active and the voice coil pickup32inactive.

Switch55is closed in the presence of a magnetic field, particularly in the presence of the magnetic field produced by telephone handset magnet22. In one embodiment of the invention, switch55is a reed switch, for example a microminiature reed switch, type HSR-003 manufactured by Hermetic Switch, Inc. of Chickasha, Okla. In a further embodiment of the invention, the switch55is a solid state, wirelessly operable switch. In an embodiment, wirelessly refers to a magnetic signal. An embodiment of a magnetic signal operable switch is a MAGFET. The MAGFET is non-conducting in a magnetic field that is not strong enough to turn on the device and is conducting in a magnetic field of sufficient strength to turn on the MAGFET. In a further embodiment, switch55is a micro-electro-mechanical system (MEMS) switch. In a further embodiment, the switch55is a magneto resistive device that has a large resistance in the absence of a magnetic field and has a very small resistance in the presence of a magnetic field. When the telephone handset magnet22is close enough to the hearing aid wearer's ear, the magnetic field produced by magnet22changes the state of switch (e.g., closes) switch55. Consequently, the base of switch51and the base of switch52are now grounded. Switches51and52stop conducting and microphone ground is no longer grounded. That is, the microphone circuit is open. Now switch52no longer draws the current away from the base of switch53and same is energized by the hearing aid voltage source through resistor59. Switch53is now conducting. Switch53connects the voice pickup coil ground to ground and completes the circuit including the voice coil pickup32and signal processing circuit34. Accordingly, the switching circuit40activates either the microphone (default) input31or the voice coil (magnetic field selected) input32but not both inputs simultaneously.

In operation, switch55automatically closes and conducts when it is in the presence of the magnetic field produced by telephone handset magnet22. This eliminates the need for the hearing aid wearer to find the switch, manually change switch state, and then answer the telephone. The wearer can conveniently, merely pickup the telephone handset and place it by his\her ear whereby hearing aid10automatically switches from receiving microphone (acoustic) input to receiving pickup coil (electromagnetic) input. That is, a static electromagnetic field causes the hearing aid to switch from an audio input to a time-varying electromagnetic field input. Additionally, hearing aid10automatically switches back to microphone input after the telephone handset14is removed from the ear. This is not only advantageous when the telephone conversation is complete but also when the wearer needs to talk with someone present (microphone input) and then return to talk with the person on the phone (voice coil input).

The above described embodiment of the switching circuit40describes a circuit that grounds an input and open circuits the other inputs. It will be recognized that the switching circuit40, in an embodiment, connects the power source to an input and disconnects the power source to the other inputs. For example, the collectors of the transistors51and53are connected to the power source. The switch55remains connected to ground. The emitter of transistor51is connected to the power input of the microphone31. The emitter of the transistor53is connected to the power input of the voice coil32. Thus, switching the switch55causes the power source to be interrupted to the microphone and supplied to the voice coil pickup32. In an embodiment, switching circuit40electrically connects the signal from one input to the processing circuit34and opens (disconnects) the other inputs from the processing circuit34.

While the disclosed embodiment references an in-the-ear hearing aid, it will be recognized that the inventive features of the present invention are adaptable to other styles of hearing aids including over-the-ear, behind-the-ear, eye glass mount, implants, body worn aids, etc. Due to the miniaturization of hearing aids, the present invention is advantageous to many miniaturized hearing aids.

FIG. 4shows hearing aid70. The hearing aid70includes a switching circuit40, a signal processing circuit34and an output speaker36as described herein. The switching circuit40includes a magnetic field responsive, solid state circuit. The switching circuit40selects between a first input71and a second input72. In an embodiment, the first input71is an omnidirectional microphone, which detects acoustical signals in a broad pattern. In an embodiment, the second input72is a directional microphone, which detects acoustical signals in a narrow pattern. The omnidirectional, first input71is the default state of the hearing aid70. When the switching circuit40senses the magnetic field, the switch changes state from its default to a magnetic field sensed state. The magnetic field sensed state causes the hearing aid70to switch from its default mode and the directional, second input72is activated. In an embodiment, the activation of the second input72is mutually exclusive of activation of the first input71.

In use with a telephone handset, e.g.,14shown inFIG. 1, hearing aid70changes from its default state with omnidirectional input71active to its directional state with directional input72active. Thus, hearing aid70receives its input acoustically from the telephone handset. In an embodiment, the directional input72is tuned to receive signals from a telephone handset.

In an embodiment, switching circuit40includes a micro-electro-mechanical system (MEMS) switch. The MEMS switch includes a cantilevered arm that in a first position completes an electrical connection and in a second position opens the electrical connection. When used in the circuit as shown inFIG. 3, the MEMS switch is used as switch55and has a normally open position. When in the presence of a magnetic field, the cantilevered arm shorts the power supply to ground. This initiates a change in the operating state of the hearing aid input.

FIG. 5shows an embodiment of a hearing aid80according to the teachings of the present invention. Hearing aid80includes at least one input81connected to a signal processing circuit34, which is connected to an output speaker36. In an embodiment, hearing aid80includes two or more inputs81(one shown). The input81includes a signal receiver83that includes two nodes84,85. Node84is connected to the signal processing circuit34and to one terminal of a capacitor86. In an embodiment, node84is the negative terminal of the input81. In an embodiment, node84is the ground terminal of the input81. Node85is connected to one pole of a magnetically operable switch87. In an embodiment, the switch87is a mechanical switch, such as a reed switch. In an embodiment, the switch87is a solid-state, magnetically actuated switch circuit. In an embodiment, the switch87is a micro-electro-mechanical system (MEMS). In an embodiment, the solid state switch87is a MAGFET. In an embodiment, the solid state switch87is a giant magneto-resistivity (GMR) sensor. In an embodiment, the switch87is normally open. The other pole of switch87is connected to the second terminal of capacitor86and to the signal processing circuit34. Switch87automatically closes when in the presence of a magnetic field. When the switch87is closed, input81provides a signal that is filtered by capacitor86. The filtered signal is provided to the signal processing circuit34. The capacitor86acts as a filter for the signal sent by the input81to the signal processing circuit34. Thus, switch87automatically activates input81and filter86when in the presence of a magnetic (wireless) field or signal. When the magnetic field is removed, then the switch automatically opens and electrically opens the input81and filter86from the signal processing circuit34.

FIG. 6shows a further hearing aid90. Hearing aid90includes at least one input81having nodes84,85connected to signal processing circuit34, which is connected to output speaker36. Node85is connected to first pole of switch87. Node84is connected to a first terminal of filter86. The second pole of switch87is connected to the second terminal of filter86. In an embodiment, the switch87is normally open. Accordingly, in the default state of hearing aid90, the signal sensed by input81is sent directly to the signal processing circuit34. In the switch active state of hearing aid90, the switch87is closed and the signal sent from the input81is filtered by filter86prior to the signal being received by the signal processing circuit34. TheFIG. 6embodiment provides automatic signal filtering when the switch87, and hence the hearing aid90, is in the presence of a magnetic field.

FIG. 7shows a further hearing aid100that includes input81, signal processing circuit34and output system36. The input81is connected to a plurality of filtering circuits1011,1012,1013. Thus, signal generated by the input81is applied to each of the filters101. Each of the filtering circuits101provides a different filter effect. For example, the first filter is a low-pass filter. The second filter is a high-pass filter. The third filter is a low-pass filter. In an embodiment, at least one of filtering circuits1011,1012,1013includes an active filter. Each of the filters101are connected to a switching circuit102. In an embodiment, the switching circuit102is a magnetically actuatable switch as described herein. The switching circuit102determines which of the filters101provides a filtered signal to the signal processing circuit34. The processing circuit34sends a signal to the output system36for broadcasting into the car of the hearing aid wearer. The switching circuit102in the absence of a magnetic field electrically connects the first filter1011to the signal processing circuit34and electrically opens the second filter1012and third filter1013. The switching circuit102in the presence of a magnetic field opens the first filter1011and electrically connects at least one of the second filter1012and third filter1013to the signal processing circuit34. In an embodiment, the second and third filters provide a band-pass filter with both being activated by the switching circuit102. While the embodiment ofFIG. 7shows the switching circuit102positioned between the filters and the hearing aid signal processing circuit34, the switching circuit102is positioned between the input81and the filtering circuits1011,1012,1013in an embodiment of the present invention. In this embodiment, the switching circuit102only supplies the input signal from input81to the selected filtering circuit(s)1011,1012,1013.

FIG. 8shows an embodiment of the present invention including a hearing aid110having a magnetic field sensor115. The magnetic field sensor115is connected to a selection circuit118. The selection circuit118controls operation of at least one of a programming circuit120, a signal processing circuit122, output processing circuit124and an input circuit126. The sensor115senses a magnetic field or signal and outputs a signal to the selection circuit118, which controls at least one of circuits120,122,124and126based on the signal produced by the magnetic field sensor115. The signal output by sensor115includes an amplitude level that may control which of the circuits that is selected by the selection circuit118. That is, a magnetic field having a first strength as sensed by sensor115controls the input126. A magnetic field having a second strength as sensed by sensor115controls the programming circuit120. The magnetic field as sensed by sensor115then varies from the second strength to produce a digital programming signal. In an embodiment, the signal output by sensor115includes digital data that is interpreted by the selection circuit to select at least one of the subsequent circuits. The selection circuit118further provides a signal to the at least one of the subsequent circuits. The signal controls operation of the at least one circuit.

In an embodiment, the signal from the selection circuit118controls operation of a programming circuit120. Programming circuit120provides hearing aid programmable settings to the signal processing circuit122. In an embodiment, the magnetic sensor115and the selection circuit118produce a digital programming signal that is received by the programming circuit120. Hearing aid110is programmed to an individual's specific hearing assistance needs by providing programmable settings or parameters to the hearing aid. Programmable settings or parameters in hearing aids include, but are not limited to, at least one of stored program selection, frequency response, volume, gain, filtering, limiting, and attenuation. The programming circuit120programs the programmable parameters for the signal processing circuit122of the hearing aid110in response to the programming signal received from the magnetic sensor115and sent to the programming circuit120through selection circuit118.

In an embodiment, the signal from selection circuit118directly controls operation of the signal processing circuit122. The signal received by the processing circuit122controls at least one of the programmable parameters. Thus, while the signal is sent by the magnetic sensor115and the selection circuit118, the programmable parameter of the signal processing circuit122is altered from its programmed setting based on the signal sensed by the magnetic field sensor115and sent to the signal processing circuit122by the selection circuit118. It will be appreciated that the programmed setting is a factory default setting or a setting programmed for an individual. In an embodiment, the alteration of the hearing aid settings occurs only while the magnetic sensor115senses the magnetic field. The hearing aid110returns to its programmed settings after the magnetic sensor115no longer senses the magnetic field.

In an embodiment, the signal from selection circuit118directly controls operation of the output processing circuit124. The output processing circuit124receives the processed signal, which represents a conditioned audio signal to be broadcast into a hearing aid wearer's ear, from the signal processing circuit122and outputs a signal to the output128. The output128includes a speaker that broadcasts an audio signal into the user's ear. Output processing circuit124includes filters for limiting the frequency range of the signal broadcast from the output128. The output processing circuit124further includes an amplifier for amplifying the signal between the signal processing circuit122and the output. Amplifying the signal at the output allows signal processing to be performed at a lower power. The selection circuit118sends a control signal to the output processing circuit124to control the operation of at least one of the amplifying or the filtering of the output processing circuit124. In an embodiment, the output processing circuit124returns to its programmed state after the magnetic sensor115no longer senses a magnetic field.

In an embodiment, the signal from the selection circuit118controls operation of the input circuit126to control which input is used. For example, the input circuit126includes a plurality of inputs, e.g., an audio microphone and a magnetic field input or includes two audio inputs. In an embodiment, the input circuit126includes an omnidirectional microphone and a directional microphone. The signal from the selection circuit118controls which of these inputs of the input circuit126is selected. The selected input sends a sensed input signal, which represents an audio signal to be presented to the hearing aid wearer, to the signal processing circuit122. In a further example, the input circuit126includes a filter circuit that is activated and/or selected by the signal produced by the selection circuit118.

FIG. 9shows an embodiment of the magnetic sensor115. Sensor115includes a full bridge140that has first node connected to power supply (Vs) and a second node connected ground. The bridge140includes third and fourth nodes whereat the sensed signal is output to firther hearing aid circuitry. A first variable resistor R1is connected between the voltage source and the third node. A second variable resistor R2is connected between ground and the fourth node. The first and second variable resistors R1and R2are both variable based on a wireless signal. In an embodiment, the wireless signal includes a magnetic field signal. A first fixed value resistor R3is connected between the voltage source and the fourth node. A second fixed value resistor R4is connected between ground and the third node. The bridge140senses an electromagnetic field produced by a source142and produces a signal that is fed to an amplifier143. Both the first and second variable resistors R1and R2vary in response to the magnetic field produced by magnetic field source142. Amplifier143amplifies the sensed signal. A low pass filter144filters high frequency components from the signal output by the amplifier143. A threshold adjust circuit145, which is controlled by threshold control circuit146, adjusts the level of the signal prior to supplying it to the selection circuit118. In an embodiment, the threshold adjust circuit145holds the level of the signal below a maximum level. The maximum level is set by the threshold control circuit146.

FIG. 10shows a further embodiment of magnetic sensor115, which includes a half bridge150. The half bridge150includes two fixed resistors R5, R6connected in series between a voltage source and the output node. Bridge150further includes two variable resistors R7, R8connected in series between ground and the output node. The two variable resistors R7, R8sense the electromagnetic field produced by the magnetic field source142to produce a corresponding signal at the output node. The amplifier143, filter144, threshold adjust circuit145and selection circuit118are similar to the circuits described herein.

The magnetic sensor115, in either the full bridge140or half bridge150, includes a wireless signal responsive, solid state device. The solid state sensor115, in an embodiment, includes a giant magnetoresistivity (GMR) device, which relies on the changing resistance of materials in the presence of a magnetic field. One such GMR sensor is marketed by NVE Corp. of Eden Prairie, Minn. under part no. AA002-02. In one embodiment of a GMR device, a plurality of layers are formed on a substrate or wafer to form an integrated circuit device. Integrated circuit devices are desirable in hearing aids due to their small size and low power consumption. A first layer has a fixed direction of magnetization. A second layer has a variable direction of magnetization that depends on the magnetic field in which it is immersed. A nonmagnetic, conductive layer separates the first and second magnetic layers. When the direction of magnetization of the first and second layers are the same, the resistance across the GMR device layer is low. When the direction of magnetization of the second layer is at an angle with respect to the first layer, then the resistance across in the layers increases. Typically, the maximum resistance is achieved when the direction of magnetization are at an angle of about 180 degrees. Such GMR devices are manufactured using VLSI fabrication techniques. This results in magnetic field sensors having a small size, which is also desirable in hearing aids. In an embodiment, a GMR sensor of the present invention has an area of about 130 mil by 17 mil. It will be appreciated that smaller GMR sensors are desirable for use in hearing aids if they have the required sensitivity and bandwidth. Further, some hearing aids are manufactured on a ceramic substrate that will form a base layer on which a GMR sensor is fabricated. GMR sensors have a low sensitivity and thus must be in a strong magnetic field to sense changes in the magnetic field. Further, magnetic field strength depends on the cube of the distance from the source. Accordingly, when the GMR sensor is used to program a hearing aid, the magnetic field source142must be close to the GMR sensor. As a example, a programming coil of the source142is positioned about 0.5 cm from the GMR sensor to provide a strong magnetic field to be sensed by the magnetic field sensor115.

When the GMR sensor is used in the hearing aid circuits described herein, the GMR sensor acts as a switch when it senses a magnetic field having at least a minimum strength. The GMR sensor is adapted to provide various switching functions. The GMR sensor acts as a telecoil switch when it is placed in the DC magnetic field of a telephone handset in a first function. The GMR sensor acts as a filter-selecting switch that electrically activates or electrically removes a filter from the signal processing circuits of a hearing aid in an embodiment. The GMR sensor acts to switch the hearing aid input in an embodiment. For example, the hearing aid switches between acoustic input and magnetic field input. As a further example, the hearing aid switches between omni-directional input and directional input. In an embodiment, the GMR sensor acts to automatically turn the power off when a magnetic field of sufficient strength changes the state, i.e., increases the resistance, of the GMR sensor.

The GMR sensor is adapted to be used in a hearing aid to provide a programming signal. The GMR sensor has a bandwidth of at least 1 MHz. Accordingly, the GMR sensor has a high data rate that is used to program the hearing aid during manufacture. The programming signal is a digital signal produced by the state of the GMR sensor when an alternating or changing magnetic field is applied to the GMR sensor. For example, the magnetic field alternates about a threshold field strength. The GMR sensor changes its resistance based on the magnetic field. The hearing aid circuit senses the change in resistance and produces a digital (high or low) signal based on the GMR sensor resistance. In a further embodiment, the GMR sensor is a switch that activates a programming circuit in the hearing aid. The programming circuit in an embodiment receives audio signals that program the hearing aid. In an embodiment, the audio programming signal is broadcast through a telephone network to the hearing aid. Thus, the hearing aid is remotely programmed over a telephone network using audio signals by non-manually switching the hearing aid to a programming mode. In an embodiment, the hearing aid receives a variable magnetic signal that programs the hearing aid. In an embodiment, the telephone handset produces the magnetic signal. The continuous magnetic signal causes the hearing aid to switch on the programming circuit. The magnetic field will remain above a programming threshold. The magnetic field varies above the programming threshold to produce the programming signal that is sensed by the magnetic sensor and programs the hearing aid. In a further embodiment, a hearing aid programmer is the source of the programming signal.

The solid state sensor115, in an embodiment, is an anisotropic magneto resistivity (AMR) device. An AMR device includes a material that changes its electrical conductivity based on the magnetic field sensed by the device. An example of an AMR device includes a layer of ferrite magnetic material. An example of an AMR device includes a crystalline material layer. In an embodiment, the crystalline layer is an orthorhombic compound. The orthorhombic compound includes RCu2 where R=a rare earth element). Other types of anisotropic materials include anisotropic strontium and anisotropic barium. The AMR device is adapted to act as a hearing aid switch as described herein. That is, the AMR device changes its conductivity based on a sensed magnetic field to switch on or off elements or circuits in the hearing aid. The AMR device, in an embodiment, is adapted to act as a hearing aid programming device as described herein. The AMR device senses the change in the state of the magnetic field to produce a digital programming signal in the hearing aid.

The solid state sensor115, in an embodiment, is a spin dependent tunneling (SDT) device. Spin dependent tunneling (SDT) structures include an extremely thin insulating layer separating two magnetic layers. The conduction is due to quantum tunneling through the insulator. The size of the tunneling current between the two magnetic layers is modulated by the magnetization directions in the magnetic layers. The conduction path must be perpendicular to the plane of a GMR material layer since there is such a large difference between the conductivity of the tunneling path and that of any path in the plane. Extremely small SDT devices with high resistance are fabricated using photolithography allowing very dense packing of magnetic sensors in small areas. The saturation fields depend upon the composition of the magnetic layers and the method of achieving parallel and antiparallel alignment. Values of a saturation field range from 0.1 to 10 kA/m (1 to 100 Oe) offering the possibility of extremely sensitive magnetic sensors with very high resistance suitable for use with battery powered devices such as hearing aids. The SDT device is adapted to be used as a hearing aid switch as described herein. The SDT device is further adapted to provide a hearing aid programming signals as described herein.

Hearing aids are powered by batteries. In an embodiment, the battery provides about 1.25 Volts. A magnetic sensor, e.g., bridges140or150, sets the resistors at 5K ohms, with the variable resistors R1, R2or R7, R8varying from the 5K ohm dependent on the magnetic field. In this embodiment, the magnetic sensor140or150would continuously draw about 250 μA. It is desirable to limit the power draw from the battery to prolong the battery life. One construction for limiting the power drawn by the sensor140or150is to pulse the supply voltage Vs.FIG. 11shows a pulsed power circuit180that receives the 1.25 Volt supply from the hearing aid battery181. Pulsed power circuit180includes a timer circuit that is biased (using resistors and capacitors) to produce a 40 Hz pulsed signal that has a pulse width of about 2.8 μsec. and a period of about 25.6 μsec for a duty cycle of about 0.109. Such, a pulsed power supply uses only about a tenth of the current that a continuous power supply would require. Thus, with a GMR sensor that continuously draws 250 μA, would only draw about 25 μA with a pulsed power supply. In the specific embodiment, the current drain on the battery would be about 27 μA (0.109*250 μA). Accordingly, the power savings of a pulsed power supply versus a continuous power supply is about 89.1%.

FIG. 12shows an embodiment of a GMR sensor circuit190that operates as both a hearing aid state changing switch and as a programming circuit. Circuit190includes a sensing stage192, followed by a high frequency signal stage193, which is followed by a bi-state sensing and switch stage201. The hearing aid state changing switch is adaptable to provide any of bi-states of the hearing aid, for example, changing inputs, changing filters, turning the hearing aid on or off, etc. The GMR sensor circuit190includes a full bridge192that receives a source voltage, for example, Vs or the output from the pulse circuit180. Vs is, in an embodiment, the battery power. The bridge192outputs a signal to both the signal stage193and the switch stage201. The positive and negative output nodes of the full bridge192are respectively connected to the non-inverting and inverting terminals of an amplifier194through capacitors195,196. The amplifier is part of the signal stage193. In an embodiment, the output197of the amplifier194is a digital signal that is used to program the hearing aid. The hearing aid programming circuit, e.g., programming circuit120, receives the digital signal197from the amplifier194. The signal197, in an embodiment, is the audio signal that is inductively sensed by bridge192and is used as an input to the hearing aid signal processing circuit.

The switching stage201includes filters to remove the high frequency component of the signal from the induction sensor. The positive and negative output nodes of the full bridge192are each connected to a filter198,199. Each filter198,199includes a large resistor (1M ohm) and a large capacitor (1 μf). The filters198,199act to block false triggering of the on/off switch component200of the circuit190. The signals that pass filters198,199are fed through a series of amplifiers to determine whether an electromagnetic field is present to switch the state of the hearing aid. An output205is the on/off signal from the on/off switch component200. The on/off signal is used to select one of two states of the hearing aid. The state of the hearing aid, in an embodiment, is between an audio or electromagnetic field input. In another embodiment, the state of the hearing aid is either an omni-directional input or directional input. In an embodiment, the state of the hearing aid is a filter acting on a signal in the hearing aid or not. In an embodiment, the signal205is sent to a level detection circuit206. Level detection circuit206outputs a digital (high or low) signal207based on the level of signal205. In this embodiment, signal207is the signal used for switching the state of the hearing aid.

FIG. 13shows a saturated core circuit1300for a hearing aid. The saturated core circuit1300senses a magnetic field and operates a switch or provides a digital programming signal. A pulse circuit1305connects the saturated core circuit to the power supply Vs. Pulse circuit1305reduces the power consumption of the saturated core circuit1300to preserve battery life in the hearing aid. The pulse circuit1305in the illustrated embodiment outputs a 1 MHz signal, which is fed to a saturatable core, magnetic field sensing device1307. In an embodiment, the device includes a magnetic field sensitive core wrapped by a fine wire. The core in an example is a 3.0×0.3 mm core. In an embodiment, the core is smaller than 3.0×0.3 mm. The smaller the core, the faster it responds to magnet fields and will saturate faster with a less intense magnetic field. An example of a saturated core is a telecoil marketed by Tibbetts Industries, Inc. of Camden, Me. However, the present invention is not limited to the Tibbetts Industries telecoil. In a preferred embodiment of the invention, the saturatable core device1307is significantly smaller than a telecoil so that the device will saturate faster in the presence of the magnetic field. The device1307changes in A.C. impedance based on the magnetic field surrounding the core. The core has a first impedance in the presence of a strong magnetic field and a second impedance when outside the presence of a magnetic field. A resistor1308connects the device1307to ground. In an embodiment, the resistor1308has a value of 100 KOhms. The node intermediate the device1307and resistor1308is a sensed signal output that is based on the change in impedance of the device1307. Accordingly, the saturable core device1307and resistor1308act as a half bridge or voltage divider. The electrical signal produced by the magnetic field sensing device1307and resistor1308is sent through a diode D1to rectify the signal. A filter1309filters the rectified signal and supplies the filtered signal to an input of a comparator1310. The comparator1310compares the signal produced by the filter and magnetic field sensor to a reference signal to produce output signal1312. In an embodiment, the signal output through the core device1307varies +/−40 mV depending on the magnetic field in which the saturable core device1307is placed. In an embodiment, it is preferred that the magnetic field is of sufficient strength to move the saturable core device into saturation. While device1307is shown as a passive device, in an embodiment of the present invention, device1307is a powered device. In an embodiment, the saturatable device1307acts a non-manual switch that activates or removes circuits from the hearing aid circuit. For example, the saturatable device1307acts to change the input of the hearing aid in an embodiment. In a further embodiment, the saturated core circuit1300activates or removes a filter from the hearing aid circuit based on the state of the output1312. In a further embodiment, the saturatable core device1307is adapted to be a telecoil switch. In a further embodiment, the saturatable core device1307is adapted to act as a automatic, non-manual power on/off switch. In a further embodiment, the saturatable core1307is a programming signal receiver.

FIG. 14shows a system1401including a hearing aid1405and a hearing aid storage receptacle1410. Receptacle1410is cup-like with an open top1411, an encircling sidewall1412upstanding from a base1413. The receptacle1410is adapted to receive the hearing aid1405and store it adjacent a magnetic field source1415. The receptacle base1413houses the magnetic field source1415. Thus, when the hearing aid1405is in the receptacle (shown in solid line inFIG. 14), the hearing aid is in the magnetic field. In an embodiment, the magnetic field experienced by the hearing aid in the receptacle is the near field. When the hearing aid1405is out of receptacle (broken line showing inFIG. 14), the hearing aid is out of the magnetic field, i.e., the magnetic field does not have sufficient strength as sensed by the magnetic field sensor of hearing aid1405to trigger a state changing signal in the hearing aid1405. In an embodiment, the hearing aid1405includes a magnetically-actuated switch1406. The magnetically-actuated switch1406is a normally on (conducting) switch that connects the power supply to the hearing aid circuit. When the hearing aid1405is in the receptacle, the magnetically-actuated switch changes to a non-conducting state and the power supply is electrically disconnected from the hearing aid circuit. Thus, hearing aid1405is placed in a stand-by mode. The stand-by mode reduces power consumption by the hearing aid. This extends hearing aid battery life. Moreover, this embodiment eliminates the need for the hearing aid wearer to manually turn off the hearing aid after removing it. The wearer merely places the hearing aid1405in the storage receptacle1410and the hearing aid1405turns off or is placed in a stand-by mode. Non-essential power draining circuits are turned off. Non-essential circuits include those that are used for signal processing that are not needed when the hearing aid wearer removes the hearing aid. The stand-by mode is used so that any programmable parameters stored in the hearing aid1405are saved in memory by power supplied to the hearing aid memory. The programmable parameters are essential parameters that are stored in the hearing aid and should not be deleted with the power being turned off. The programmed parameters include the volume level. Thus, when the hearing aid1405is removed from the receptacle1410, the hearing aid is automatically powered by the normally on switch1406electrically10reconnecting the hearing aid signal processing circuit to the power supply and the hearing aid1405returns to the stored volume level without the wearer being forced to manually adjust the volume level of the hearing aid.

The hearing aid storage system1401, in an embodiment, includes a magnetic field source1415that produces a magnetic field that is significantly greater, e.g., at least 3-4 times as great, as the constant magnetic field and/or the varying magnetic field of a telephone handset. This allows the hearing aid1405to include both the automatic switch40that alternates inputs based on a magnetic field of a first threshold and the automatic power-off switch1406that turns off the hearing aid based on a magnetic field of a higher threshold. Thus, hearing aid1405includes automatically switching between inputs, filters, settings, etc. as described herein and automatically powering down to preserve battery power when the hearing aid is in the storage receptacle1410.

In another embodiment of the present invention, the hearing aid1405further includes a rechargeable power supply1407and a magnetically actuated switching circuit1406as described herein. The rechargeable power supply1407includes at least one of a rechargeable battery. In an embodiment, rechargeable power supply1407includes a capacitor. In an embodiment, a power induction receiver is connected to the rechargeable power supply1407through the switching circuit1406. The receptacle1410includes a power induction transmitter1417and magnetic field source1415. When the hearing aid1405is positioned in the receptacle1410, the magnetic switch1406turns on a power induction receiver of the rechargeable power supply1407. The power induction receiver receives a power signal from the power induction transmitter1417to charge the power supply1407. Thus, whenever the hearing aid1405is stored in the receptacle1410, the hearing aid power supply1407is recharged. In an embodiment, the magnetically actuated switch1406electrically disconnects the hearing aid circuit from the hearing aid power supply1407and activates the power induction receiver to charge the hearing aid power supply. As a result, the hearing aid power supply1407is recharged when the hearing aid is not in use by the wearer.

In a further embodiment, the system1401includes a cleaning source1430connected to the storage receptacle1410. The cleaning source1430supplies sonic or ultrasonic cleaning waves inside the receptacle1411. The waves are adapted to clean the hearing aid1405. Accordingly, the hearing aid1405is automatically cleaned when placed in the receptacle1411.

FIG. 15shows a further embodiment of the hearing aid switch1406that includes an indicator circuit1450. Indicator circuit1450is adapted to produce an indicator signal to the hearing aid user. In an embodiment, the indicator circuit1450is connected to a magnetic field sensor, e.g. sensor115,190or1300. The indicator circuit provides an indication signal that indicates that the magnetic field sensor190or1300is sensing the magnetic field. In an embodiment, the indicator circuit indicates that the hearing aid has been disconnected from the power supply. In an embodiment, the indicator circuit indicates that the hearing aid power supply is being recharged by the recharging circuit1417. Indicator circuit1450includes a comparator1455that receives the output signal from the magnetic field sensor circuit190or1300and compares the received output signal to a threshold value and based on the comparison sends a signal to an indicator1460that produces the indicator signal. The indicator signal is a visual signal produced by a low power LED.

FIG. 16shows a hearing aid switch circuit1600. Circuit1600switches the power from one input to another input. In an embodiment, one input is an induction input and the other input is an audio input. In an embodiment, circuit1600exclusively powers one of the inputs. Circuit1600includes a power supply1601connected to a resistor1603at node1604. Hence, node1604is at a high, non-groung potential. In an embodiment, the power supply is a hearing aid battery power supply. In an embodiment, the power supply is in the range of 1.5 to 0.9 volts. In an embodiment, the resistor1603is a 100 KOhm. The resistor1603is connected to a non-manual switch1605that is connected to ground. Switch1605, in an embodiment, is a magnetically actuatable switch as described herein. An input to first inverter1607is connected to node1604. The output of inverter1607is connected to the input of a first hearing aid input1609and an input of a second inverter1611. The output of the second inverter1611is connected to a second hearing aid input1613. In an embodiment, first and second inverters1607and1611are Fairchild ULP-A NC7SV04 inverters. The inverters have an input voltage range from 0.9V to 3.6V.

The circuit1600has two states. In the first state, which is illustrated, the switch1605is open. The node1604is at a high voltage. Inverter1607outputs a low signal, which is supplied to both the first input1609and the second inverter1611. The first input1609is off when it receives a low signal. The second inverter1611outputs a high, on signal to the second input1613. Accordingly, in the open switch state of circuit1600, the first input1609is off and the second input1613is on. When in the presence of a magnetic field, switch1605closes. Node1604is connected to ground and, hence, is at a low potential. Inverter1607outputs a high, on signal to the first input1609and second inverter1611. The first input1609is on, i.e., powered. The second inverter1611outputs a low, off signal to second input1613. Accordingly, in the closed switch state of circuit1600, the first input1609is on and the second input1613is off. In an embodiment, the first hearing aid input1609is an induction input and the second hearing aid input1613is an audio input. Thus, in the switch open state, the second, audio input1613is on or powered and the first, induction input1609is off or unpowered. In the switch closed state, the first, induction input1609is on or powered and the second, audio input1613is off. The circuit1600is used as an automatic, induction telephone signal input circuit.

FIG. 17shows a hearing aid switch circuit1700. Circuit1700is similar to circuit1600, like elements are designated with the same two least significant digits and the two most significant digit refer to the figure on which they appear. In circuit1700, the switch1705is connected to the voltage supply1701. Resistor1703is connected between node1704and ground. The input of first inverter1707is connected to node1704. The output of first inverter1707is connected to the first input1709and the input of the second inverter1711. The output of the second inverter1711is connected to the second input1713.

The circuit1700has two states. In the first state, which is illustrated, the switch1705is open. The node1704is grounded by resistor1703and is at a low potential. Inverter1707outputs a high signal, which is supplied to both the first input1709and the second inverter1711. The first input1709is on when it receives a high signal. The second inverter1711outputs a low, off signal to the second input1713. Accordingly, in the open switch state of circuit1700, the first input1709is on and the second input1713is off. When in the presence of a magnetic field, switch1705closes. Node1704is connected to the voltage supply through closed switch1705and, hence, is at a high potential. Inverter1707outputs a low, off signal to the first input1709and second inverter1711. The first input1709is off, i.e., unpowered. The second inverter1711outputs a high, on signal to second input1713. Accordingly, in the closed switch state of circuit1700, the first input1709is off and the second input1713is on. In an embodiment, the first hearing aid input1709is an audio input and the second hearing aid input1713is an induction input. Thus, in the switch open state, the first, audio input1709is on or powered and the second, induction input1713is off or unpowered. In the switch closed state, the first, audio input1709is off and the second, induction input1713is on or powered. The circuit1700is used as an automatic, induction telephone signal input circuit. Further, circuit1700does not continually incur the loss associated with resistor1703. The default state of the circuit1700is with the resistor1703grounded and no power drain occurs across resistor1703. In circuit1600, there is a continuous power loss associated with resistor1603. Power conservation and judicious use of the battery power in a hearing aid is a significant design characteristic.

FIG. 18shows a hearing aid switch circuit1800. Circuit1800includes a supply voltage1801connected to an induction, first hearing aid input1809and a non-manual switch1805. Switch1805, in an embodiment, is a magnetic field actuatable switch as described herein. A resistor1803connects a node1804to ground. Switch1805is connected to node1804. Inverter1807is connected to node1810. Both first input1809and an audio, second hearing aid input1813are connected to node1810. Second input1813is connected to ground. Circuit1800has two states. In a first, switch open state node1804is connected to ground through resistor1803. The inverter1807outputs a high signal to node1810. The high signal turns on or powers the second input1813. The high signal at node1810is a high enough voltage to hold the potential across the first input1809to be essential zero. In an embodiment, the high signal output by inverter1807is essentially equal to the supply voltage1801. Thus, the first input1809is off In a second, switch closed state, node1804is at a high potential. Inverter1807outputs a low signal. In an embodiment, the low signal is essentially equal to ground. The potential across the first input1809is the difference between the supply voltage and the low signal. The potential across the first input1809is enough to turn on the first input. The low signal is low enough so that there is no potential across the second input1813. Thus, the first input1809is on and the second input1813is off in the closed switch state of circuit1800.

While the above embodiments described in conjunction withFIGS. 16-18include inverters, it will be recognized that the other logic circuit elements could be used. The logic circuit elements include NAND, NOR, AND and OR gates. The use of logic elements, inverters and other logic gates, is a preferred approach as these elements use less power than the transistor switch circuit as shown inFIG. 3.

The above embodiments described in conjunction withFIGS. 16-18include switching between hearing aid inputs by selectively powering the inputs based on the state of a switch. It will be recognized that the switching circuits are adaptable to the other switching applications described herein. For example, the switching circuits1600,1700, or1800switch between an omni-directional input and a directional input.

FIG. 19shows a hearing aid switch circuit1900. Circuit1900is similar to circuit1600described above with like elements being identified by reference numerals having the same two least significant digits and the two larger value digits being changed from 16 to 19. For example, the supply voltage is designated as1601inFIG. 16 and 1901inFIG. 19. Switching circuit1900includes an electrical connection from the output of inverter1907to the signal processor1922. Consequently, inverter1907outputs a low signal to first input1909, second inverter1911and signal processor1922with the magnetic field sensing switch1905being open. Inverter1907outputs a high signal to first input1909, second inverter1911and signal processor1922with the magnetic field sensing switch1905being closed. Thus, the signal processor1922receives a hearing aid state signal from the inverter1907. In an embodiment, when the state signal is low, then the signal processor1907is adapted to optimize the hearing aid signal processing for a second (microphone) input from second input (microphone)1913. Second input (microphone)1913is in an active state as it has received a high or on signal from second inverter1911. The signal processing circuit1922, in an embodiment, optimizes the signal processing by selecting stored parameters, which are optimized for second input signal processing, from a memory. In an embodiment, the memory is an integrated circuit memory that is part of the signal processor1922. When the state signal is high, then the signal processor1922is adapted to optimize the hearing aid signal processing for a first input from first input (telecoil induction)1909. First input1909is in an active state as it has received a high or on signal from first inverter1907. The signal processing circuit1922, in an embodiment, optimizes the signal processing by selecting stored parameters, which are optimized for first input (induction) signal processing, from the memory. Other stored parameters in the memory of signal processor1922include automatic gain control, frequency response, and noise reduction for respective embodiments of the present disclosure.

FIG. 20shows a hearing aid switch circuit2000. Circuit2000is similar to circuit1700described above with like elements being identified by reference numerals having the same two least significant digits and the two larger value digits being changed from 17 to 20. For example, the supply voltage is designated as1701inFIG. 17 and 2001inFIG. 20. Switching circuit2000includes an electrical connection from the output of first inverter2007to the signal processor2022. Consequently, inverter2007outputs a high signal to first input2009, second inverter2011and signal processor2022with the magnetic field sensing switch2005being open. Inverter2007outputs a low signal to first input2009, second inverter2011and signal processor2022with the magnetic field sensing switch2005being closed. Thus, signal processor2022receives a hearing aid state signal from the inverter2007. In an embodiment, when the state signal is high, then the signal processor2022is adapted to optimize the hearing aid signal processing for a first input signal from first input (microphone)2009. First input2009is in an active state as it has received a high or on signal from first inverter2007. The signal processing circuit2022, in an embodiment, optimizes the signal processing by selecting stored parameters, which are optimized for microphone signal processing, from a memory. In an embodiment, the memory is an integrated circuit memory that is part of the signal processor2022. When the state signal is low or off, then the signal processor2022is adapted to optimize the hearing aid signal processing for a second input signal from second input (telecoil)2013. Second input2013is in an active state as it has received a high or on signal from second inverter2011. The signal processing circuit2022, in an embodiment, optimizes the signal processing by selecting stored parameters, which are optimized for second signal (induction) processing, from the memory. Other stored parameters in the memory of signal processor2022include automatic gain control, frequency response, and noise reduction for respective embodiments of the present disclosure.

FIG. 21shows a hearing aid switch circuit2100. Circuit2100includes elements that are substantially similar to elements described above. Like elements are identified by reference numerals having the same two least significant digits and the two larger value digits being changed 21. For example, the supply voltage is designated as1601inFIG. 16,1701inFIG. 17 and 2101inFIG. 21. Switching circuit2100includes a selection circuit that selects signal processing parameters. Selection circuit includes a logic gate2107. In the illustrated embodiment, the logic gate2107is a NAND gate. A first input of the NAND gate2107is connected to the power source2101. Thus, this input to the NAND gate is always high. A second input of the NAND gate2107is connected to the power source2201through a resistor and to a first terminal of magnetic field sensing switch2105. Consequently, the state of the switch2105determines the output of the NAND gate2107during operation of the hearing aid switch2100. Operation of hearing aid switch2100is defined as when the switch is powered. During the off or non-operational state of the hearing aid switch circuit2100, the supply voltage2101is turned off and the NAND gate2107will always produce a low output to conserve power, which is a consideration in designing hearing aid circuits. The switch2105is normally open. Thus, both inputs to the NAND gate2107are high and its output signal is high. The output of NAND gate2107is connected to signal processor2122. Signal processor2122includes a switch that upon the change of state of the NAND gate output signal changes a parameter setting in signal processor2122. In an embodiment, when the magnetic field sensing switch2105senses a magnetic field, switch2105closes. The second input to NAND gate2107goes low and NAND gate output goes low. This triggers the switch of signal processor2122to change parameter settings. In an embodiment, signal processor only changes its parameter settings when the signal from NAND gate2107shifts from high to low. In an embodiment, the parameter settings include parameters stored in a memory of signal processor2122. In an embodiment, a first parameter setting is adapted to process input from first input2109. A second parameter setting is adapted to process input from second input2113. In an embodiment, the first parameter setting is selected with the output signal from NAND gate2107being high. The second parameter setting is selected with the output signal from NAND gate2107being low. Accordingly, the switching circuit2100can select parameters that correspond to the type of input, e.g., microphone or induction inputs or directional and omni-directional inputs. The hearing aid thus more accurately produces sound for the hearing aid wearer. In an embodiment, the switch in signal processor2122is adapted to progress from one set of stored parameters to the next each time the signal from NAND gate2107goes low.

FIG. 22shows a hearing aid switch circuit2200. Circuit2200includes elements that are substantially similar to elements described above. Like elements are identified by reference numerals having the same two least significant digits and the two larger value digits being changed22. For example, the supply voltage is designated as2101inFIG. 21is2201inFIG. 22. Switching circuit2200includes a selection circuit that is adapted to select parameters for signal processing. The selection circuit includes a logic gate2207having its output connected to signal processor2222. In the illustrated embodiment, the logic gate2207is a NAND gate. A first input of the NAND gate2207is connected to the power source2201. Thus, this input to the NAND gate is always high. A second input of the NAND gate2207is connected to the power source2201through a magnetic field sensing switch2105. The second input of NAND gate2207is also connected to ground through a resistor R. Consequently, the state of the switch2205determines the output of the NAND gate2207during operation of the hearing aid switch2200. Operation of hearing aid switch2200is defined as when the switch is powered. During the off or non-operational state of the hearing aid switch circuit2200, the supply voltage2201is turned off and the NAND gate2207will always produce a low output to conserve power, which is a consideration in designing hearing aid circuits. Switch2205is normally open. Thus, the first input to the NAND gate2207is high and the second input to NAND gate2207is low. Thus, the NAND gate output signal is low. Signal processor2222includes a switch that upon the change of state of the NAND gate output signal changes a parameter setting in signal processor2222. In an embodiment, when the magnetic field sensing switch2205senses a magnetic field, switch2205closes. The second input to NAND gate2207goes high and NAND gate output goes high. This triggers the switch of signal processor2222to change parameter settings. In an embodiment, signal processor only changes its parameter settings when the signal from NAND gate2107shifts from low to high. In an embodiment, the parameter settings include parameters stored in a memory of signal processor2222. In an embodiment, a first parameter setting is adapted to process input from first input2209. A second parameter setting is adapted to process input from second input2213. In an embodiment, the first parameter setting is selected with the output signal from NAND gate2207being low. The second parameter setting is selected with the output signal from NAND gate2207being high. Accordingly, the switching circuit2200can select parameters that correspond to the type of input, e.g., microphone or induction inputs. The hearing aid thus more accurately produces sound for the hearing aid wearer.

It will be appreciated that the selection of parameters for specific inputs can be combined with theFIGS. 2-18embodiments. For example, the magnetic field sensor changing state not only switches the input but also generates a signal, for example, through logic circuit elements, that triggers the signal processing circuit to change its operational parameters to match the type of input.

Possible applications of the technology include, but are not limited to, hearing aids. Various types of magnetic field sensors are described herein for use in hearing aids. One type is a mechanical reed switch. Another type is a solid state magnetic responsive sensor. Another type is a MEMS switch. Another type is a GMR sensor. Another type is a core saturation circuit. Another type is anisotropic magneto resistive circuit. Another type is magnetic field effect transistor. It is desirable to incorporate solid state devices into hearing aids as solid state devices typically are smaller, consume less power, produce less heat then discrete components. Further the solid state switching devices can sense and react to a varying magnetic field at a sufficient speed so that the magnetic field is used for supplying programming signals to the hearing aid.

Those skilled in the art will readily recognize how to realize different embodiments using the novel features of the present invention. Several other embodiments, applications and realizations are possible without departing from the present invention. Consequently, the embodiment described herein is not intended in an exclusive or limiting sense, and that scope of the invention is as claimed in the following claims and their equivalents.