METHOD FOR OPERATING A HEARING AID

Description

[0001] The invention relates to a method for operating a hearing aid. Furthermore, the invention relates to a hearing aid and a system comprising a hearing aid and a charger. The hearing aid includes a charging port with two electrical contacts.

[0002] People with hearing loss typically use a hearing aid. This usually involves an electromechanical transducer that captures ambient sound. The resulting electrical signals are amplified by an amplifier circuit and then delivered to the ear canal via another electromechanical transducer, often in the form of a receiver. The captured sound signals are usually also processed, typically by a signal processor within the amplifier circuit. The amplification is adjusted to compensate for the hearing loss of the hearing aid user.

[0003] Electrical energy is required to operate both the converter and the amplifier circuitry. This is usually supplied by a battery housed within the hearing aid casing. This allows the user freedom of movement. When the battery is depleted, it needs to be replaced. The casing typically has a flap for easy access to the battery.

[0004] A disadvantage of this design is that leaks can allow foreign particles or moisture to penetrate the housing, potentially damaging the hearing aid components inside, such as the amplifier circuitry. Consequently, a relatively extensive seal is required. Due to the limited space available, this increases design and manufacturing costs. Furthermore, the relatively small size of the flap often necessitates additional tools for operation, and user error is a possibility.

[0005] An alternative approach is to use a rechargeable battery. When the battery is depleted, it simply needs to be recharged to restore functionality; no removal of the device is required. This allows for a largely sealed housing and simplifies operation. For charging, the hearing aid typically has a charging port with two electrical contacts. These contacts interact with two corresponding contacts on a charger. For example, the corresponding contacts may be directly connected mechanically, and then disconnected after charging is complete. Alternatively, the contacts and corresponding contacts may interact via electrical coils, resulting in inductive energy exchange between the hearing aid and the charger.The charger itself is usually connected to a power supply network via a plug. The electrical voltage between the mating contacts, which is used to charge the hearing aid, is generated based on the electrical voltage supplied by the power supply network.

[0006] Once the hearing aid is charged, the user usually removes it from the charger for immediate use. To increase user convenience, the hearing aid is automatically put into operating mode as soon as it is removed from the charger. This is typically detected by a drop in the voltage across the contacts, which then ceases to interact with the corresponding contacts. However, it is also possible that the charger plug is disconnected from the power supply. In this case, the voltage across the corresponding contacts drops, and consequently, so does the voltage across the contacts themselves. However, the hearing aid should generally not be used immediately; instead, it should be operated in an energy-efficient manner until it is actually needed.To prevent the hearing aid from switching to operating mode, it is necessary to additionally determine whether the hearing aid is still connected to the charger when the electrical voltage at the contacts drops. For this purpose, a third contact is used, or a sensor, such as a Hall sensor, is present, which detects an electric field generated by the opposing contacts. However, this results in additional components, which increases manufacturing costs.

[0007] From DE 10 2007 013 420 A1 it is known to equip a hearing device with a switching device in order to disconnect charging contacts, which are arranged on the surface of the housing and which serve to charge a battery of the hearing device, from the battery and to connect the battery to an amplifier circuit when the battery is not being charged.

[0008] In JP 2009 021910 A, a rechargeable hearing aid is disclosed. This can be charged inductively.

[0009] The invention is based on the objective of providing a particularly suitable method for operating a hearing aid, as well as a particularly suitable hearing aid and a particularly suitable system comprising a hearing aid and a charger, wherein in particular comfort is increased and / or manufacturing costs are reduced.

[0010] With regard to the method, this problem is solved according to the invention by the features of claim 1, with regard to the hearing aid by the features of claim 5, and with regard to the system by the features of claim 7. Advantageous further developments and embodiments are the subject of the respective dependent claims.

[0011] The method is used to operate a hearing aid. The hearing aid is, for example, a headphone or includes a headphone. However, the hearing aid is preferably a hearing aid device. The hearing aid device serves to support a person suffering from a reduction in hearing ability. In other words, the hearing aid device is a medical device by means of which, for example, partial hearing loss is compensated. The hearing aid device is, for example, a receiver-in-the-canal (RIC) hearing aid, an in-the-ear hearing aid such as an in-the-ear (ITC) or complete-in-the-canal (CIC) hearing aid, hearing glasses, a pocket hearing aid, a bone conduction hearing aid, or an implant. Alternatively, the hearing aid is a behind-the-ear hearing aid, which is worn behind the ear.

[0012] The hearing aid is designed and configured to be worn on the human body. In other words, the hearing aid preferably includes a retention device that allows it to be attached to the human body. Alternatively or in combination with this, the hearing aid is suitably shaped. If the hearing aid is a hearing assistance device, it is designed and configured to be placed, for example, behind the ear or within an ear canal. In particular, the hearing aid is wireless and designed and configured to be inserted, at least partially, into an ear canal.

[0013] The hearing aid preferably comprises a hearing aid housing. Essentially all other components of the hearing aid are preferably arranged within the hearing aid housing, at least preferably including any electronics, such as an amplifier circuit. For example, the hearing aid housing is either a single piece or, more preferably, made of several components. The hearing aid housing is suitably manufactured from a plastic, particularly using a plastic injection molding process. This allows for a relatively high degree of design freedom. Furthermore, the weight of the hearing aid housing is not excessively high.

[0014] The hearing aid housing contains, for example, a microphone, specifically an electromechanical sound transducer. The microphone is designed and intended for capturing ambient sound.

[0015] In particular, the microphone is electrically and / or via signal processing connected to the electronics, especially the amplifier circuit, or other electrical / electronic components of the hearing aid. These components are then used to process the signals captured by the microphone.

[0016] Preferably, the hearing aid includes a further electromechanical transducer, in particular a receiver, through which the signals processed by the amplifier circuit are delivered. For example, the receiver is also located in the hearing aid housing or in a separate housing. The two housings are connected by a cable, for example, particularly if the hearing aid is a RIC (receiver-in-canal) hearing aid.

[0017] The hearing aid includes a charging port, through which electrical energy can be supplied to the hearing aid. For this purpose, the charging port has two electrical contacts, which will be referred to simply as contacts from now on. When the hearing aid is being charged, when electrical energy is supplied, or at least when interacting with a charger, an electrical voltage is present at these contacts. The charger serves to charge the hearing aid, i.e., to supply it with electrical energy. The charger is suitable for this purpose, specifically designed and configured for this function.

[0018] The charging port is, for example, mechanically designed, and the two electrical contacts are formed, or at least comprise, by means of pogo pins, a mechanical connector, or an electrically conductive plate. The electrical contacts are, for example, integrated directly into a wall of the hearing aid housing or are located in a recess that is covered, for example, by a flap. Alternatively, the two electrical contacts are connected to an electrical coil, and charging is wireless. Advantageously, a rectifier, such as a diode rectifier, is arranged between the electrical contacts and the (electrical) coil so that a DC voltage is present at the electrical contacts when the hearing aid interacts with the charger.A capacitor or other capacitance is preferably connected between the contacts to stabilize the electrical voltage. This ensures that the voltage across the electrical contacts remains essentially constant during continuous interaction with the charger.

[0019] The charger preferably has two mating contacts. If charging is mechanical, for example via a cable, one of the mating contacts is directly connected to its corresponding contact. If charging is inductive, for example, the mating contacts are electrically connected, preferably via an inverter, to a coil. An electrical DC voltage is advantageously applied to the mating contacts.

[0020] The hearing aid preferably includes an energy storage device that provides the power supply. Advantageously, the energy storage device is used to power any electronics / transducers. The energy storage device is suitably arranged within the hearing aid housing. The energy storage device is advantageously rechargeable, and preferably a rechargeable battery. In particular, the energy storage device is connected to the two electrical contacts, for example, directly or via a charging circuit. Preferably, the charging circuit includes a voltmeter, which is designed, for example, as an analog-to-digital converter (ADC) or at least incorporates one. The charging circuit regulates or at least controls the charging of the energy storage device via the charging port. In this way, it is possible to increase the number of possible charging cycles.

[0021] The method involves detecting a drop in the electrical voltage applied to the two contacts. The voltage applied to the electrical contacts is preferably a direct current (DC) voltage. This voltage is present at the two contacts due to the interaction with the charger. This interaction, for example, charges the hearing aid. To establish this interaction, the hearing aid, preferably its charging port, is connected to the charger, particularly if charging is wireless. Alternatively, a mating connector or similar device is inserted into the charging port, ensuring direct mechanical contact with the charging port's contacts.

[0022] Once an electrical voltage is applied across the two contacts, i.e., between them, the system detects that this voltage decreases. In particular, the amplitude of the applied electrical voltage decreases, especially if an alternating voltage is applied across the two contacts. However, it is particularly preferred that a direct voltage is applied across them, and the magnitude of the electrical voltage decreases as it falls.

[0023] In In a further step, the rate of decrease of the electrical voltage is recorded, and an operating mode of the hearing aid is set accordingly. Specifically, one of several operating modes is selected, and the hearing aid is then operated according to the selected mode. This involves applying different currents to certain components of the hearing aid.

[0024] When the interaction between the charger and the hearing aid is terminated, particularly when the hearing aid is removed from the charger, this occurs relatively abruptly, causing the electrical voltage across the two contacts to drop relatively quickly. In contrast, when the charger is disconnected from its power supply or at least when power is cut off, the charger's inductances and / or capacitances allow it to continue operating for a short period, although the amount of energy exchanged between the charger and the hearing aid decreases. Consequently, the electrical voltage across the two contacts drops in a different way. Since the operating mode of the hearing aid is determined by the rate of this voltage drop, it is thus adjusted according to how the interaction is terminated.Therefore, the hearing aid will operate differently depending on whether it is detached from the charger or whether the charger itself is switched off. This method thus caters to the user's needs, increasing comfort. Furthermore, no additional components, such as sensors, are required, thereby reducing manufacturing costs.

[0025] To determine the time course of an electrical voltage, the voltage is measured at only two different points in time. For example, the time interval between these two points in time is predetermined, and the voltage is measured at each of these times. The time course is then inferred based on the magnitude of the voltage difference between the two points in time. Alternatively, the voltage values ​​are predetermined, and the time course is determined by the time interval between the points in time at which the voltage corresponds to these predetermined values. Since both variants involve only two measurements, or at least determine the time course based on only two different values, the complexity and computational effort are reduced.Therefore, the procedure is comparatively resource-efficient, and it is possible to perform the procedure even with a low-performance hearing aid.

[0026] Alternatively, to determine the time course, the electrical voltage is recorded over a comparatively long period and analyzed. For example, a Fourier analysis of the electrical voltage is performed. However, it is particularly preferred that a time derivative of the electrical voltage be created to determine the time course. Preferably, the derivative is used as the time course. For example, if the derivative has a specific maximum value, a specific minimum value, and / or a specific mean value, a specific operating mode is used, whereas a different operating mode is used if a different minimum / maximum / mean value is present. Due to the use of the derivative, accuracy is increased, and, for example, comparatively short-term fluctuations or other disturbances do not lead to a change in the operation of the hearing aid.

[0027] A standby operating mode is particularly preferred when the electrical voltage decreases more slowly than a first threshold value. For example, the difference between the electrical voltages measured at two different times, spaced a certain distance apart, is smaller than a specific value used to define the first threshold value. Alternatively, the first threshold value is determined based on the derivative, and the derivative is expediently smaller than a further threshold value. In standby mode, for example, individual components or all components of the hearing aid are switched off, or one or more components are operated with a comparatively low energy consumption, thereby limiting, for instance, a certain range of functions.If the electrical voltage drops slowly, the connection to the charger, or at least the interaction with it, remains. Therefore, it can be assumed that the charger is no longer receiving power and is simply dissipating any residual voltage. In this case, the hearing aid is unlikely to be used immediately afterward, and due to the standby mode, the hearing aid's energy consumption is reduced. Consequently, if the user subsequently wishes to use the hearing aid, it will have a comparatively high charge level. If the hearing aid was already in standby mode while charging, it is advisable to leave it in this mode.

[0028] Alternatively, or particularly preferably in combination with this, an operating mode is selected when the electrical voltage drops faster than a second limit value. For example, in this case, the difference between the two electrical voltages measured at two different times, which are at a constant time interval, is greater than a certain limit value, or the derivative, in particular a minimum, maximum, or average, is greater than another limit value. When the hearing aid is switched to operating mode, preferably some components of the hearing aid that were not previously energized are powered. In particular, a control unit or other circuit, especially a microprocessor, is switched to operating mode from a standby mode.The rapid descent of the hearing aid abruptly ends its interaction with the charger, suggesting that the hearing aid has been mechanically detached. In this case, the user usually wants to use the hearing aid immediately, and due to the procedure, no additional steps are required. Specifically, if the hearing aid was already operating in this mode, there is no change in operating mode.

[0029] It is particularly advantageous to choose the first limit value to be the same as the second limit value, so that depending on the time course of the decrease, only one of two operating modes is selected at any given time. This reduces complexity and ensures that the operation is transparent and understandable for the user.

[0030] For example, the voltage drop is detected when the amount of electrical energy fed into the energy storage device falls below a certain value. Preferably, however, the voltage drop is detected when the electrical voltage applied to the two contacts falls below a third threshold. This third threshold is expediently relatively high and is, for example, between 95% and 75%, between 90% and 70%, or between 85% and 80% of the electrical voltage applied to the electrical contacts during a charging process. Due to such a third threshold, fluctuations in the interaction between the charger and the hearing aid do not affect the charging process of the hearing aid, whereas the appropriate operating mode of the hearing aid is selected as soon as the hearing aid is disconnected from the charger or the charger is switched off.Furthermore, the procedure only requires determining the electrical voltage, thus reducing hardware requirements.

[0031] The hearing aid has a charging port with two electrical contacts. For example, the charging port can be inductive or wired. The electrical contacts are specifically adapted for each type, and a DC voltage is applied to each contact, regardless of the specific design of the charging port, when the hearing aid is being charged or interacting with a charger. The hearing aid operates according to a method that detects a drop in the voltage applied to the two contacts. Based on the rate of this voltage drop, an operating mode for the hearing aid is then selected.

[0032] In particular, the hearing aid includes a control unit that is suitable, specifically designed and configured, to carry out the procedure. The control unit is formed, for example, by means of electronics, which preferably also include a signal processor. Advantageously, the hearing aid includes an energy storage device, such as a battery, which can be charged, in particular, via the charging port. For this purpose, the energy storage device is, for example, directly electrically connected to the charging port or, more preferably, by means of a charging circuit. In particular, the charging port is a component of the charging circuit.

[0033] An analog-to-digital converter (ADC) is particularly preferred for determining the time course. Advantageously, the ADC is also used to evaluate the voltage applied to the electrical contacts, and in particular, the beginning of the voltage drop is detected by means of the ADC. The charging circuit is also preferably operated by means of the ADC. Thus, the ADC performs various tasks. Furthermore, a suitable ADC is already present in some hearing aids, so that, in particular, no additional hardware requirements exist. Therefore, manufacturing costs are not increased.

[0034] Preferably, the (digital) signals generated by the A / D converter are evaluated by electronics within the hearing aid, for example, by means of a comparator. In particular, a signal processor is used for this purpose, which is also used, for example, to process the (acoustic) output signal, preferably when the hearing aid is not charging and / or when the hearing aid is in operating mode.

[0035] The system comprises a hearing aid with a charging port featuring two electrical contacts. The system also includes a charger for charging the hearing aid, specifically its energy storage device. The charger is specifically designed and equipped for this purpose. During operation, the charger transfers electrical energy to the hearing aid, particularly to its energy storage device. In summary, a hearing aid charger is understood to be a charger specifically for a hearing aid, but the charger itself is not part of the hearing aid. The charger and the hearing aid are separate units / components of the system that can be detached from one another. However, during charging, the charger and the hearing aid interact.

[0036] In one embodiment, to establish the interaction, each mating contact is detachably mechanically connected to its corresponding contact, and the contacts and mating contacts are made of an electrically conductive material. Alternatively, the contacts and mating contacts are each electrically connected to a coil, preferably via additional components. In particular, the mating contacts are connected to the corresponding coil via an inverter, and the contacts via a rectifier. Advantageously, the contacts are also electrically connected to a capacitor. To establish the interaction, the two coils are brought close together, and the inverter is operated, in particular, such that an alternating voltage is applied to the corresponding coil.

[0037] The hearing aid operates according to a method that detects a drop in the electrical voltage applied to the two contacts. Depending on the time course of this drop, an operating mode of the hearing aid is selected.

[0038] Preferably, the two opposing contacts of the charger are connected by means of a capacitor, which thus conveniently powers the inverter. Preferably, the inverter is also operated by means of the voltage applied to the capacitor, thereby simplifying the circuit. The capacitor is particularly preferably a capacitor or at least includes a capacitor.

[0039] Due to its capacitance, the inverter continues to operate for an extended period when the charger's current is changed, resulting in a relatively slow drop in voltage at the contacts. Conversely, when the hearing aid is removed from the charger, the voltage continues to drop relatively quickly. Therefore, due to the capacitance, the rate of voltage drop is more dependent on how the interaction between the charger and the hearing aid is terminated.

[0040] The further training and advantages explained in connection with the procedure can also be applied analogously to the hearing aid / the system and to each other, and vice versa.

[0041] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 schematically simplified a system with a hearing aid and a charger, Fig. 2 a method for operating the hearing aid, and Fig. 3, 4 different time profiles of an electrical voltage applied to two electrical contacts of the hearing aid.

[0042] Corresponding parts are marked with the same reference symbols in all figures.

[0043] In Fig. 1A system 2 is shown with a hearing aid 4 in the form of a hearing aid designed and configured to be worn behind the ear of a user (user, hearing aid wearer, carrier). In other words, it is a behind-the-ear hearing aid. The hearing aid 4 comprises a hearing aid housing 6, which is manufactured from a plastic using an injection molding process. A microphone 8 is arranged inside the hearing aid housing 6. The microphone 8 is signal-coupled to an electronics unit 10, which includes a signal processing unit (not shown) with an amplifier circuit and a signal processor. The electronics unit 10 is formed by circuit elements such as electrical and / or electronic components. The signal processor is a digital signal processor (DSP) and is signal-connected to the microphone 8 via an analog-to-digital converter (ADC) (not shown).

[0044] The electronics 10 are connected to a receiver 12 via a signal connection. During operation, the receiver 12 converts an (electrical) signal provided by the electronics 10 into an output sound, i.e., sound waves. These are directed into a sound tube (not shown), one end of which is attached to the hearing aid housing 6. The other end of the sound tube is enclosed by a dome, which, in its intended state, is positioned in the user's ear canal. The electronics 10, the microphone 8, and the receiver 12 are powered by an energy storage device in the form of a battery 14, which is located in the hearing aid housing 6.

[0045] The hearing aid 4 further comprises a charging circuit 16, which is electrically connected to the battery 14 and serves to charge the battery 14. For this purpose, the charging circuit 16 includes a control unit (not shown) by means of which the voltage applied to the battery 14 is adjusted. The charging circuit 16 also includes a charging port 18, which has two contacts 20. The contacts 20 are connected to the battery 14 via the control unit (not shown). An analog-to-digital converter 21 detects the electrical voltage applied to the contacts 20 and operates the control unit accordingly. The two contacts 20 are electrically connected to each other by means of a capacitor 22 and to a rectifier 24, namely a diode rectifier. This rectifier is connected to and powered by an electrical coil 26, which is also referred to simply as a coil.

[0046] Furthermore, system 2 comprises a charger 28, which has two mating contacts 28. The mating contacts 28 are connected to and powered by a further rectifier 30. The further rectifier 30, in turn, is powered via a plug 32, which serves to electrically connect the charger 28 to a power supply network, through which a DC voltage, for example 230 V or 110 V, is supplied. The two mating contacts 28 are connected to an inverter 34, through which a coil 36 of the charger 28 is powered. In addition, the two mating contacts 28 are electrically connected to each other by means of a capacitor 38.

[0047] To charge the hearing aid 4, namely the battery 14, the plug 32 is electrically connected to the power supply network, and consequently the capacitor 38 is charged via the rectifier 30. The capacitor 38 powers the inverter 34, thus applying an alternating voltage to the coil 36 of the charger 28. This coil is located in close proximity to the charging port 18, namely the coil 26, so that an alternating voltage is induced in it. This voltage is rectified by the rectifier 24 and smoothed by the capacitor 22, so that a substantially constant DC voltage is present at the contacts 20. This voltage is detected by the analog-to-digital converter 21, and the control unit is adjusted accordingly, thus charging the battery 14.

[0048] Furthermore, the hearing aid 4 is according to a Figure 2The described method 40 is operated, which is at least partially carried out by means of the electronics 10. In a first step 42, a drop in the electrical voltage 44 applied to the two contacts 20 is detected, the temporal course of which is recorded. Figure 3 This is shown as an example. Here, the applied electrical voltage 44 is detected by the A / D converter 21, and the generated (digital) signals are fed to the electronics 10, which evaluate the signals. If the electrical voltage 44 falls below a third limit value 46, which corresponds to 80% of the electrical voltage 44 required or typically present when charging the battery 14, the drop is detected. In other words, the applied electrical voltage 44 is also monitored during charging by the A / D converter 21 and the electronics 10.

[0049] InIn a subsequent second step 48, a time course 50 of the decrease in the electrical voltage 44 is determined. In one embodiment, a time derivative 52 of the electrical voltage 44 is created for this purpose. In an alternative, to determine the time course 50, the electrical voltage 44 is recorded at two different times 54 after the decrease has been detected, the first of which coincides with the time at which the electrical voltage 44 differs from the third limit value 46. The second of which is located at a fixed time interval 56 after the first of the two times 54.

[0050] In a subsequent third step 58, an operating mode 60 of the hearing aid 4 is set depending on the time course 50 of the voltage drop. If the electrical voltage 44 drops faster than a second limit value 62, an operating mode is used as operating mode 60. The second limit value 62 is exceeded if the user manually moves the hearing aid 4 away from the charger 28. In this case, the user typically wants to use the hearing aid 4 immediately afterward. When switching to operating mode, the electronics 10, namely the signal processing unit, the amplifier circuit, and the signal processor, are put into an operating mode with increased energy consumption. Any settings stored in software or memory are also loaded, so that the hearing aid 4 is ready for use when the user puts it on.

[0051] When the hearing aid 4 is removed from the charger 28, the coil 36 of the charger 28 continues to be supplied with alternating current via the inverter 34, thus creating an electric field around it. However, due to the increasing distance, less voltage is induced in the coil 26 of the hearing aid 4. Consequently, the voltage 44 applied to the contacts 20 drops to 0 V. Since the hearing aid 4 is removed from the charger 28 relatively abruptly, the interaction between them also ends relatively abruptly. In other words, the energy transfer between the charger 28 and the hearing aid 4 is abruptly terminated.

[0052] In one variant, a specific value for the derivative 52 is used as the second limit 62, which is found in the Figure 3The second limit 62 is exceeded in the example shown by the derivative 52. In other words, the second limit 62 is exceeded when the derivative 52 is greater than the second limit 62 and thus the electrical voltage 44 drops to 0 V relatively quickly. If the time course 50 is determined based on the electrical voltage 44 recorded at the two time points 54, the second limit 62 is exceeded when the difference between the two recorded electrical voltages 44 is greater than a certain corresponding value.

[0053] If, however, plug 32 is removed from the power supply network and the position of the two tracks 26, 36 relative to each other is not changed, the capacitor 38 is no longer supplied via the additional rectifier 30. However, the inverter 34 continues to operate for a longer period due to the electrical voltage still present across the capacitor 38 and the electrical energy stored therein. Consequently, energy transfer from the charger 28 to the hearing aid 4 continues, although the electrical voltage induced in the coil 26 decreases slowly, so that the electrical voltage 44 present at the contacts 20 also drops relatively slowly.

[0054] As a result, as in Figure 4The derivative 52 is shown below the second limit value 62, which is chosen to be equal to a first limit value 64. In other words, the two limit values ​​62 and 64 are equal. Furthermore, the difference in the electrical voltage 44 measured at the specified times is greater than the corresponding determined value. In this case, a standby operating mode 60 is selected. In summary, the standby operating mode is selected when the electrical voltage 44 decreases more slowly than the first limit value 64. In the standby operating mode, the electronics 10, if this is not already the case, are operated in a mode with reduced energy consumption. For this purpose, for example, the amplifier circuit, the signal processing circuit, and / or the signal processor are completely switched off. The control unit is also switched off.As a result, the energy consumption of hearing aid 4 is reduced, and it can be stored for a comparatively long period. If the user wishes to use hearing aid 4, it is necessary to put it into operating mode, which is done by means of a corresponding input, in particular by pressing a switch.

[0055] The invention is not limited to the embodiment described above. Rather, other variants of the invention can also be derived by a person skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the embodiment can also be combined with one another in other ways without departing from the subject matter of the invention. Reference symbol list

[0056] 2 System 4 Hearing aid 6 Hearing aid housing 8 Microphone 10 Electronics 12 Receiver 14 Battery 16 Charging circuit 18 Charging port 20 Contact 21 A / D converter 22 Capacitor 24 Rectifier 26 Coil 28 Counter contact 30 Another rectifier 32 Plug 34 Inverter 36 Charger coil 38 Capacitance 40 Procedure 42 First step 44 Electrical voltage 46 Third limit 48 Second step 50 Time course 52 Derivative 54 Time point 56 Time span 58 Third step 60 Operating mode 62 Second limit 64 First limit

Claims

1. Method (40) for operating a hearing aid (4), which comprises a charging connection (18) having two electrical contacts (20), in which - a decrease of an electrical voltage (44) applied at the two contacts (20) is detected, and - an operating mode (60) of the hearing aid (4) is set depending on the time profile (50) of the decrease, wherein to determine the time profile (50) the electrical voltage (44) is only detected at two different times (54), or wherein a time derivative (52) of the electrical voltage (44) is generated to determine the time profile (50).

2. Method (40) according to Claim 1, characterized in that a standby operating mode is selected when the electrical voltage (44) decreases more slowly than a first limiting value (64).

3. Method (40) according to either of Claims 1 to 2, characterized in that a working mode is selected when the electrical voltage (44) decreases faster than a second limiting value (62).

4. Method (40) according to any of Claims 1 to 3, characterized in that the decrease is detected when the electrical voltage (44) applied at the two contacts (20) falls below a third limiting value (46).

5. Hearing aid (4), which comprises a charging connection (16) having two electrical contacts (20), and which is operated according to a method (40) according to any of Claims 1 to 4.

6. Hearing aid (4) according to Claim 5, characterized by an A / D converter (21) for determining the time profile (50) of the decrease.

7. System (2) having a charger (28), which comprises two electrical counter contacts (28) electrically connected by means of a capacitance (38), and having a hearing aid (4) according to Claim 5 or 6.