Procedures for operating a hearing aid and hearing aid

Abstract

The hearing aid (2) comprises a digital signal processing unit (4), a first electrical component, in particular a loudspeaker (6), and a second electrical component, in particular a microphone (12), wherein the first electrical component is controlled by the signal processing unit (4) via two electrical conductors, each designated as interference line (10A, 10B), and the second electrical component is connected to an electrical connecting line designated as receiver line (12), wherein a digital control signal (SA, SB) is transmitted via each interference line (10A, 10B) during operation.To reduce and, in particular, to prevent the coupling of interference effects onto a signal transmitted via the receiver line (12), the two control signals (SA, SB) fed into the interference lines (10A, 10B) by the signal processing unit (4) are modulated such that a differential signal (D) of the two control signals (SA, SB) applied to the first electrical component (6) is formed as a bipolar control signal which alternates between exactly two voltage values ​​and that a common mode signal (C) formed from the two control signals (SA, SB) is constant.

Description

The invention relates to a method for operating a hearing device and to a hearing device.The hearing device is in particular a hearing aid device which is provided for compensating hearing damage of a person who is impaired by hearing.Hearing aids of this type, but also hearing aids in general, have a digital signal processing unit having an amplifier part, via which in particular a receiver is actuated. The receiver is typically designed as an electrodynamic loudspeaker. The receiver is regularly connected to the amplifier part of the signal processing unit via a two-wire connecting line via which a high-frequency digital and modulated control signal is transmitted during operation.In the embodiment of the receiver as an electrodynamic loudspeaker, the two control signals are applied to a coil of the receiver. In particular, for reasons of energy saving as well, the control signals are modulated (pulse width modulation or pulse density modulation) in such a way that three different voltage values are present at the receiver (-1, 0, +1).Hearing aids regularly have input transducers, in particular microphones, which convert an acoustic sound signal into an electrical signal, which is further processed by the signal processing unit and transmitted to the receiver as a processed output signal in the form of the two control signals.Furthermore, it is known to design a hearing device with a microphone which is arranged in the ear cup. This is also referred to below as a pinna microphone. It is used to produce the so-called pinna effect. The pinna microphone is arranged in the ear cup in the worn state and oriented rearward. This microphone is typically an analog microphone which is connected to the signal processing unit via a single-core connection line for transmitting an analog received signal.In particular in the case of RIC (receiver in canal) hearing aids, this single-core connection line is laid together with the two-core control line for the receiver, for example in a common hose.Furthermore, in particular analog sensors such as a temperature sensor or a pressure sensor can be providedDue to the compact design of the hearing aids, there is generally the problem that interference signals can be transmitted between different lines as a result of coupling effects. Specifically, the two-type control line leading to the receiver acts as a noise source. Signals which are transmitted via the connecting line, for example to the pinna microphone, are very sensitive with respect to interference. To avoid disturbing such signals, different measures are known, such as, for example, shielding, a spatially separated laying of the different lines and / or a twisting of the lines.An object of the invention is to avoid interference in the transmission of signals.The object is achieved according to the invention by a method for operating a hearing device having the features of claim 1 and by a hearing device having the features of claim 11.The advantages and preferred embodiments listed with regard to the method are also to be transferred analogously to the hearing device and vice versa.The hearing device is in particular a hearing aid device. The hearing device generally has a digital signal processing unit, a first electrical component, in particular a receiver and specifically an electrodynamic loudspeaker, and a second electrical component, in particular a microphone. The first electrical component is actuated by the signal processing unit via two electrical line conductors, each referred to as a fault line, of a two-conductor control line, and the second electrical component is connected to an electrical connection line, referred to as a receiver line. In operation, a digital control signal is transmitted via each interferer line. Due to parasitic effects, in particular parasitic capacitances, an interference signal is coupled into the receiver line from each interferer line. In order to keep an influence on a signal which is transmitted via the receiver line at least low or to avoid it, the signal processing unit is now designed in such a way that the control signals fed into the two interferer lines during operation are modulated in such a way that a differential signal of the two control signals present at the first electrical component, that is to say especially at the receiver, is designed as a bipolar control signal which alternately changes between exactly two voltage values and that furthermore a common mode signal formed from the two control signals is constant. The common mode signal is formed by the averaged voltage of the voltage values of the two control signals. The applied control signal forms in particular the supply voltage for the first electrical component, in particular for the receiver.As mentioned at the beginning, for reasons of energy consumption, the control signals are modulated in such a way that the control signal (differential signal) of the two control signals present at the receiver changes between the three voltage levels -1, 0 +1. Such a modulation, however, has the disadvantage in long control lines laid close to one another and especially in pinna microphones that the effect of crosstalk represents a particular problem.In order to avoid such problems, it is provided in the present case that the difference signal changes only between two voltage values, in particular between +1 and -1. This embodiment is based on the consideration that, due to the typically capacitive coupling effects, these two control signals are coupled into the receiver line and are summed there. Furthermore, this embodiment is based on the consideration that the common mode signal is constant as a result of the specific modulation of the control signals and therefore no crosstalk is generated. Crosstalk is generated only in the case of a varying common mode signal, as is the case in the case of conventional modulation of the control signals and driving of the receiver.The present embodiment is thus based on the fact that a symmetrical, bipolar control signal is intentionally applied to the receiver, so that a common mode signal is constant in order to at least reduce interference effects due to crosstalk. The present invention intentionally accepts higher energy consumption.The receiver line is typically connected to the signal processing unit for further processing of the signal transmitted via the receiver line. The signal processing unit evaluates this signal transmitted via the receiver line. Furthermore, as described at the beginning, the signal processing unit is also used for generating the processed output signal, which is preferably fed into the interferer line in the form of the two control signals.If a bipolar control signal present at the electrical component (i.e. the bipolar difference signal of the two control signals present at the first electrical component) is referred to here, this is understood to mean that this bipolar control signal changes back and forth between exactly two voltage values, namely in particular between a positive and a negative voltage value (+1 and -1). This voltage value is in particular the positive and negative voltage value of a voltage supply, for example of a battery. The voltage value is typically in the range of a few volts (e.g., 1V to 5V).To generate the bipolar control signal present at the electrical component, the two control signals are preferably in phase opposition, namely in such a way that one control signal has the voltage value +1 and the other control signal has the voltage value 0. This ensures that the bipolar differential signal / control signal applied to the first component (receiver) assumes exclusively the values +1 and -1.The receiver line is in particular a so-called single-end line, in which the second component is thus connected only via a single signal wire for signal transmission. Therefore, the receiver line-unlike the control line-is not just a two-wire signal line.In a preferred embodiment, the second component is preferably an analog component which feeds an analog signal into the receiver line.The second component is preferably a microphone, and in particular a so-called pinna microphone.The hearing device is therefore preferably also an RIC hearing device (receiver in canal). The receiver line is guided together with the two-core control line in the direction of the receiver, preferably within a common hose. The two-core control line and the (single-core) receiver line are therefore guided closely next to one another over a comparatively long distance.Alternatively or additionally, the second component is an in particular analog sensor, for example a temperature sensor or a pressure sensor.The second component is preferably connected via the receiver line to an analog-to-digital converter, which converts the analog signal into a digital signal. This is then usually processed further by the digital signal processing unit.The control signals are preferably generated by an amplifier part of the signal processing unit. This amplifier part is in particular an H-bridge and / or a so-called class D amplifier.An exemplary embodiment of the invention is explained in more detail below with reference to the figures. These show FIG. 1 shows a greatly simplified circuit diagram of a hearing device in a simplified block diagram representation, FIG. 2 shows a combined representation of a plurality of signal curves, and FIG. 3 shows an H-bridge with a connected receiver.The hearing device 2 shown in simplified form in FIG. 1 is in particular a hearing aid device which is configured to compensate for user-specific hearing damage. For this purpose, the hearing aid device is set up and set in a manner known per se, so that in particular a frequency-dependent amplification, for example, adapted to the user-specific hearing damage is carried out. The hearing device 2 generally has a receiver / signal converter (not shown in the figure), for example a microphone, which usually converts an acoustic signal into a digital input signal and passes it on to a digital signal processing unit 4, in which the digital input signal is processed, in particular amplified, in accordance with the user-specific settings and is passed on as a processed output signal to a receiver, in particular designed as a loudspeaker 6.For this purpose, the digital signal processing unit 4 comprises in particular an amplifier part 8, which preferably has an H-bridge and / or is designed as a so-called class D amplifier. This is connected to the loudspeaker 6 via a two-wire control line 10 and thus via two wire conductors. The line cores are referred to below as interferer lines 10A, 10B.The output signal prepared by the control unit 4 is transmitted via this two-wire control line 10. For this purpose, a modulated (pulse-width-modulated or pulse-density-modulated) control signal S A, S B, is transmitted via the two interferer lines 10A, 10B. These control signals S A, S B are therefore each composed of a (modulated) pulse sequence of individual positive voltage pulses having the amplitude +1 (+1 means that the voltage value of a supply voltage, for example the battery voltage, is present).Furthermore, the hearing device 2 has a pinna microphone 12 which, for the purpose of supplying voltage, is connected on the one hand via a supply line 14 to a supply voltage 16 and on the other hand via a ground line 18 to a ground potential 20.Furthermore, the pina microphone 12 is connected via a receiver line 22 to the signal processing unit 4, specifically in particular to an analog-to-digital converter 24. In the exemplary embodiment, a filter 26, in particular a low-pass filter, is arranged upstream of the analog-to-digital converter 24.The hearing device 2 is preferably an RIC hearing device. The hearing device has a main part, not shown in detail here, with its own housing, wherein the main part is typically worn behind the ear. In the closed housing of the main part, a plurality of the components of the hearing device 2 and in particular the signal processing unit 4 are contained.The two-core control line 10 and the receiver line 22 and typically also the supply line 14 are guided together close to one another and in particular within a common hose from the main part to an earpiece of the hearing device 2 remote therefrom, which earpiece is inserted into the ear, specifically into the earpiece or into the ear canal of the user. In addition, the ground line 18 is frequently also additionally laid together with the aforementioned lines and in particular together with in the common hose (not shown). This earpiece has the loudspeaker 6. The broken line in FIG. 1 depicts the interface between the main part and the components arranged outside the main part.During operation, acoustic signals are detected via the pina microphone 12 and are forwarded as an analog (data) signal via the receiver line 22 to the signal processing unit 4.This analog signal is very sensitive, in particular due to the direct proximity to the control line 10, with respect to interference signals which are coupled into the receiver line 22 due to parasitic effects on the two interferer lines 10A, 10B due to the control signals S A, S B.To illustrate these parasitic effects, parasitic, capacitive coupling paths 28 are drawn in FIG. 1. These are not physical, wired line connections but merely parasitic effects. For each control signal SA, SB, these parasitic effects couple an interference signal corresponding to the respective control signal SA, SB into the receiver line 22.In order to reduce or avoid an influence of interference of these parasitic effects on the signal in the receiver line 22, it is now provided that the control signals SA, SB coupled into the two control lines 10A, 10B by the signal processing unit 4 and in particular by the amplifier part 8 are modulated in such a way that the total signal (control signal or voltage) present at the loudspeaker 6, which is a difference signal D (in this regard, see also FIG. 2 ) between the two control signals SA, SB, is designed as a bipolar signal which only has the two voltage states +1 and -1.As can be seen from the pulse sequences of the control signals SA, SB indicated in FIG. 1, these control signals SA, SB are designed in antiphase. In the present case, this is understood to mean that one control signal SA has the voltage value +1, when the other control signal SB has the voltage value 0 and vice versa.At the same time, it is also achieved that a common mode signal C (cf. FIG. 2 ) has a constant value of (SA+SB) / 2=0.5. This is represented in FIG. 1 by the sum signal S sum.Due to the constant common mode signal C, it is ensured that no disturbing influences are coupled into the receiver line 22, since in the present configuration disturbing influences are generated for the (analog) data on the receiver line only in the case of a varying common mode signal.Different signal curves are explained with reference to FIG. 2:In the first row, an analog signal A is shown, for example, as an oscillating wave. This analog signal A is represented by a digital signal. Namely, the oscillating wave is mapped by suitable pulse sequences forming the control signals S A, S B (lines 2 and 3).These control signals S A, S B are applied to the loudspeaker 6 and therefore define its control signal or the voltage applied to it. This is formed by the difference voltage D=S A- S B(4. line). This voltage value alternately assumes the voltage values +1 and -1.Furthermore, the fifth line of FIG. 2 also shows the common mode signal C, which has a constant signal level with the voltage value 0.5.With reference to FIG. 3, it will be explained how the pulse sequences of the control signals S A, S B are generated with the aid of an H-bridge as amplifier part 8: this has a total of 4 switches S1-S4, which, as illustrated, are connected to a supply voltage and to a ground potential (GND). The supply voltage is in particular the voltage of a supply battery of the hearing device 2. the supply voltage is represented by the plus symbol (+) and the ground potential is represented by the minus symbol (-). One fault line 10A is connected between the switch pairs S 1 and S 2, and the other fault line 10B is connected between the switch pairs S 3 and S 4. Their ends are in turn connected to the loudspeaker 6, namely to its coil 30. The supply voltage is present between the switches S 1 and S 3 and the switches s 2 and S 4 are each connected to the ground potential.For the voltage state control signal S A= +1 and control signal S B= 0 the switches S1 and S4 are closed, while S2 and S3 are open (first switch position configuration). The difference signal D applied to the loudspeaker 6, in particular to the coil 30, or the voltage applied to the coil is as follows:For the voltage state control signal S A= 0 and control signal S B= +1 the switches S2 and S3 are closed, while S1 and S4 are open (second switch position configuration). The difference signal D applied to the loudspeaker 6, in particular to the coil 30, or the voltage applied to the coil is as follows:By suitable actuation of the switches S1-S4, the pulse sequences shown in FIG. 2 are obtained. The H-bridge is merely switched between the two switch position configurations discussed above.The principle described here with the specifically designed control signals S A, S B is not limited to the application example described here with the pinna microphone 12 and the RIC hearing device. Alternatively to the pinna microphone 12, the second component is, for example, an in particular analog sensor, for example a temperature sensor or also a pressure sensor. Instead of an RIC hearing device, other hearing device types can generally also be involved, for example a BTE hearing device (Behind The Ear).List of reference characters2 Hearing device 4 Signal processing unit 6 Loudspeaker 8 Amplifier part 10 Control line 10'A, 10B Interferer line 12 Pina microphone 14 Supply line 16 Supply voltage 18 Ground line 20 Ground potential 22 Receiver line 24 Analog-to-digital converter 26 Filter 28 Coupling line 30 Coil S A, S B Control signal S sum Sum signal A Analog signal D Difference signal C Common mode signal

Claims

Method for operating a hearing device (2) which has a digital signal processing unit (4), a first electrical component, in particular a loudspeaker (6), and a second electrical component, in particular a microphone (12), wherein the first electrical component is actuated by the signal processing unit (4) via two electrical line conductors which are each referred to as a interferer line (10A, 10B), and the second electrical component is connected to an electrical connection line which is referred to as a receiver line (12), wherein in operation a digital control signal (S A, S B) is transmitted via each interferer line (10A, 10B), characterized in that the two control signals (S A, which are fed into the interferer lines (10A, 10B) by the signal processing unit (4), S B) can be modulated in such a way that a differential signal (D) of the two control signals (S A, S B) applied to the first electrical component is designed as a bipolar control signal, which alternately changes between exactly two voltage values, and that a common mode signal (C) formed from the two control signals (S A, S B) is furthermore constant.Method according to the preceding claim, in which the bipolar control signal switches between the voltage values +1 and -1.Method according to one of the preceding claims, in which the control signals (S A, S B) are in phase opposition, so that the one control signal (S A) has the voltage value +1 and the other control signal (S B) has the voltage value 0.Method according to one of the preceding claims, in which the receiver line (12) is a single-end line.Method according to one of the preceding claims, in which the second component is an analog component which feeds an analog signal into the receiver line (12).Method according to one of the preceding claims, in which the second component is a microphone, in particular a pinna microphone (12).Method according to any one of the preceding claims, wherein the second component is an analogue sensor.Method according to one of the preceding claims, in which the second component is connected via the receiver line (12) to an analog-to-digital converter (24) of the signal processing unit (4).Method according to one of the preceding claims, in which the control signals are generated by an amplifier part (8) of the signal processing unit (4), in particular by an H-bridge.Method according to one of the preceding claims, in which the two line cores are guided jointly with the receiver line (12) and the hearing device (2) is in particular an RIC hearing device (2).Hearing device (2), in particular hearing device, having - a digital signal processing unit (4), - a first electrical component, in particular a loudspeaker (6), - a second electrical component, in particular a microphone (12), - wherein the first electrical component is connected to the signal processing unit (4) via two electrical line conductors which are each referred to as an interferer line (10A, 10B), and - the signal processing unit (4) is designed to transmit a control signal (S A, S B) to the first component in operation via each interferer line (10A, 10B), - and wherein the second electrical component is connected to an electrical connection line which is referred to as a receiver line (12), characterized in that - the signal processing unit (4) is designed to transmit a control signal (S S to the first component in operation, the control signals (S A, S B) fed into the perturbation lines (10A, 10B) during operation are modulated in such a way that a differential signal of the two control signals (S A, S B) present at the first electrical component is designed as a bipolar control signal, which alternately changes between exactly two voltage values, and that a common mode signal formed from the two control signals (S A, S B) is furthermore constant.Hearing device (2) according to the preceding claim, wherein - the signal processing unit (4) has an amplifier part (8), in particular an H-bridge, via which the control signals (S A, S B) are generated, - the signal processing unit (4) is configured such that the two control signals (S A, S B) are in phase opposition, such that the one control signal has the voltage value +1 and the other control signal has the voltage value 0, - the signal processing unit (4) is configured such that the bipolar control signal changes between the voltage values +1 and -1, - the receiver line (12) is a single-end line, - the second component is an analog microphone, in particular a pinna microphone (12).

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