Method 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

[0001] The invention relates to a method for operating a hearing aid and to a hearing aid.

[0002] The hearing aid is specifically a hearing aid device designed to compensate for hearing loss in a hearing-impaired person.

[0003] Such hearing aids, and hearing aids in general, feature a digital signal processing unit with an amplifier section, which in particular controls a receiver. The receiver is typically designed as an electrodynamic loudspeaker. The receiver is usually connected to the amplifier section of the signal processing unit via a two-wire cable, through which a high-frequency digital and modulated control signal is transmitted during operation.

[0004] When the receiver is designed as an electrodynamic loudspeaker, the two control signals are applied to a coil within the receiver. Particularly for energy-saving reasons, the control signals are modulated (pulse width modulation or pulse density modulation) so that three different voltage values ​​(-1, 0, +1) are present at the receiver.

[0005] Hearing aids regularly feature input transducers, especially 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.

[0006] It is also known to design a hearing aid with a microphone positioned in the auricle. This is subsequently referred to as a pinna microphone. It is used to generate the so-called pinna effect. When worn, the pinna microphone is positioned in the auricle and oriented backwards. This microphone is typically an analog microphone, which is connected to the signal processing unit via a single-wire connection cable for transmitting an analog received signal.

[0007] Especially with RIC (Receiver in Canal) hearing aids, this single-wire connection cable is laid together with the two-wire control cable for the receiver, for example in a common tube.

[0008] Furthermore, analog sensors, such as a temperature sensor or a pressure sensor, may be provided.

[0009] Due to the compact design of hearing aids, a common problem is that coupling effects can transmit interference between different lines. The dual control line leading to the receiver, in particular, acts as a source of interference. Signals transmitted via the connecting line, for example to the Pinna microphone, are very susceptible to interference. Various measures are known to prevent interference with such signals, such as shielding, routing the different lines as separately as possible, and / or twisting the lines together.

[0010] One object of the invention is to avoid interference in the transmission of signals.

[0011] The problem is solved according to the invention by a method for operating a hearing aid with the features of claim 1 and by a hearing aid with the features of claim 11.

[0012] The advantages and preferred designs mentioned with regard to the procedure can also be applied analogously to the hearing aid and vice versa.

[0013] The hearing aid is specifically a hearing assistance device. It generally comprises 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 controlled by the signal processing unit via two electrical conductors of a two-wire control line, each referred to as an interference line, and the second electrical component is connected to an electrical connecting line referred to as a receiver line. During operation, a digital control signal is transmitted via each interference line. Due to parasitic effects, in particular parasitic capacitances, an interference signal is coupled from each interference line into the receiver line.To minimize or eliminate interference with a signal transmitted via the receiver line, the signal processing unit is designed such that the control signals injected into the two interference lines during operation are modulated in such a way that the differential signal of the two control signals applied to the first electrical component, specifically the receiver, is a bipolar control signal that alternates between exactly two voltage values. Furthermore, a common-mode signal derived from the two control signals remains constant. This common-mode signal is formed by the average voltage of the voltage values ​​of the two control signals. The applied control signal, in particular, serves as the supply voltage for the first electrical component, specifically the receiver.

[0014] As mentioned at the beginning, the control signals are modulated for energy consumption reasons in such a way that the control signal (difference signal) at the receiver alternates between the three voltage levels -1, 0, and +1. However, such modulation has the disadvantage with long, closely spaced control lines, and especially with pinna microphones, that crosstalk is a particular problem.

[0015] To avoid such problems, the differential signal is designed to switch only between two voltage values, specifically between +1 and -1. This design is based on the consideration that, due to typical capacitive coupling effects, these two control signals are coupled into the receiver line and summed there. Furthermore, this design is based on the consideration that the specific modulation of the control signals ensures that the common mode signal remains constant, thus preventing crosstalk. Crosstalk is only generated with a varying common mode signal, as is the case with conventional modulation of the control signals and control of the receiver.

[0016] The present design is based on the fact that a symmetrical, bipolar control signal is deliberately 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 deliberately accepts a higher energy consumption as a result.

[0017] 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 above, the signal processing unit is also used to generate the processed output signal, which is preferably fed into the interference line in the form of the two control signals.

[0018] When referring to a bipolar control signal applied to the electrical component (i.e., the bipolar difference signal of the two control signals applied to the first electrical component), this means that this bipolar control signal alternates between exactly two voltage values, specifically between a positive and a negative voltage value (+1 and -1). This voltage value is, in particular, the positive and negative voltage values ​​of a power supply, such as a battery. The voltage value is typically in the range of a few volts (e.g., 1V to 5V).

[0019] To generate the bipolar control signal applied to the electrical component, the two control signals are preferably out of phase, such that one control signal has a voltage value of +1 and the other control signal has a voltage value of 0. This ensures that the bipolar differential signal / control signal applied to the first component (receiver) assumes only the values ​​+1 and -1.

[0020] The receiver line is specifically a so-called single-end line, meaning the second component is connected for signal transmission via only a single signal wire. Therefore, unlike the control line, the receiver line is not a two-wire signal line.

[0021] In a preferred embodiment, the second component is preferably an analog component that feeds an analog signal into the receiver line.

[0022] Preferably, the second component is a microphone, and in particular a so-called pinna microphone.

[0023] The hearing aid is therefore preferably a RIC (Receiver-in-Canal) hearing aid. The receiver cable and the two-wire control cable are routed together towards the receiver, preferably within a shared tube. The two-wire control cable and the (single-wire) receiver cable are thus routed closely alongside each other over a relatively long distance.

[0024] Alternatively or additionally, the second component is a sensor, particularly an analog one, such as a temperature sensor or a pressure sensor.

[0025] 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 typically processed further by the digital signal processing unit.

[0026] The control signals are preferably generated by an amplifier section of the signal processing unit. This amplifier section is in particular an H-bridge and / or a so-called class D amplifier.

[0027] An embodiment of the invention is explained in more detail below with reference to the figures. These show FIG 1 a highly simplified circuit diagram of a hearing aid in a simplified block diagram representation, FIG 2 a combined representation of several signal waveforms, and FIG 3 an H-bridge with connected receiver.

[0028] At the in FIG 1 The simplified hearing aid 2 is, in particular, a hearing aid device designed to compensate for a user-specific hearing impairment. For this purpose, the hearing aid device is set up and adjusted in a manner known per se, such that, in particular, amplification is adapted to the user-specific hearing impairment, for example, frequency-dependent amplification. The hearing aid 2 generally has a receiver / signal converter (not shown in the figure), for example, a microphone, which typically converts an acoustic signal into a digital input signal and forwards this to a digital signal processing unit 4. In the digital input signal, the digital input signal is processed according to the user-specific settings, in particular amplified, and forwarded as a processed output signal to a receiver, in particular a loudspeaker 6.

[0029] The digital signal processing unit 4 comprises, in particular, an amplifier section 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 conductors. The conductors are hereinafter referred to as interference lines 10A, 10B.

[0030] The output signal processed 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 SA, SB, is transmitted via each of the two interference lines 10A, 10B. These control signals SA, SB therefore each consist of a (modulated) pulse sequence of individual positive voltage pulses with an amplitude of +1 (+1 means that the voltage value of a supply voltage, e.g., the battery voltage, is present).

[0031] Furthermore, the hearing aid 2 has a Pinna microphone 12, which is connected to a supply voltage 16 via a supply line 14 on the one hand and to a ground potential 20 via a ground line 18 on the other.

[0032] Furthermore, the Pina microphone 12 is connected via a receiver line 22 to the signal processing unit 4, and 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.

[0033] The hearing aid 2 is preferably a RIC (receiver-in-canal) hearing aid. The hearing aid has a main unit, not shown in detail here, with its own housing, the main unit typically being worn behind the ear. A plurality of the components of the hearing aid 2, and in particular the signal processing unit 4, are contained within the closed housing of the main unit.

[0034] The two-wire control cable 10, the receiver cable 22, and typically also the power supply cable 14 are routed together closely, and in particular within a common tube, from the main unit to an earpiece of the hearing aid 2 located away from it. This earpiece is inserted into the ear, specifically into the auricle or ear canal of the user. Additionally, the ground cable 18 is often also routed together with the aforementioned cables and, in particular, together with the other cables, within the same tube (not shown). This earpiece contains the loudspeaker 6. The in FIG 1 The dashed line represents the interface between the main part and the components located outside the main part.

[0035] During operation, 12 acoustic signals are captured via the Pina microphone and forwarded as an analog (data) signal via the receiver line 22 to the signal processing unit 4.

[0036] This analog signal is particularly sensitive to interference signals due to its immediate proximity to the control line 10, which are coupled into the receiver line 22 by parasitic effects on the control signals SA, SB on the two interference lines 10A, 10B.

[0037] To illustrate these parasitic effects, in FIG 1 Parasitic, capacitive coupling paths 28 are shown. These are not physical, wired connections but merely parasitic effects. For each control signal SA, SB, a corresponding interference signal is coupled into the receiver line 22 by these parasitic effects.

[0038] To reduce or avoid the 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 section 8 are modulated in such a way that the total signal (drive signal or voltage) applied to the loudspeaker 6, which is a differential signal D (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.

[0039] As shown by the in FIG 1 As can be seen from the indicated pulse sequences of the control signals SA and SB, these control signals are antiphase. In this context, this means that one control signal, SA, has a voltage value of +1 when the other control signal, SB, has a voltage value of 0, and vice versa.

[0040] At the same time, this also ensures that a Common Mode Signal C (cf. FIG 2 ) has a constant value of (SA + SB) / 2 = 0.5. This is in FIG 1 represented by the sum signal S sum.

[0041] Due to the constant common mode signal C, it is ensured that no interference is coupled into the receiver line 22, since in the present configuration interference for the (analog) data on the receiver line is only generated with a varying common mode signal.

[0042] Based on the FIG 2 Different signal waveforms are explained: In the first line, an analog signal A is initially represented as an oscillating wave. This analog signal A is then represented by a digital signal. Specifically, the oscillating wave is represented by suitable pulse sequences that form the control signals SA and SB (lines 2 and 3).

[0043] These control signals SA and SB are applied to loudspeaker 6 and therefore define its control signal, or rather the voltage applied to it. This is formed by the differential voltage D = SA - SB (4th line). This voltage alternates between the values ​​+1 and -1.

[0044] Furthermore, in the fifth line of the FIG 2 The Common Mode Signal C is also shown, which has a constant signal level with a voltage value of 0.5.

[0045] Based on FIG 3 It will be explained how the pulse sequences of the control signals SA and SB are generated using an H-bridge as amplifier section 8: This section has a total of four switches, S1-S4, which are connected to a supply voltage and a ground potential (GND) as shown. The supply voltage is, in particular, the voltage of a power supply battery for the hearing aid 2. The supply voltage is represented by the plus symbol (+) and the ground potential by the minus symbol (-). One interference line, 10A, is connected between switch pairs S1 and S2, and the other interference line, 10B, is connected between switch pairs S3 and S4. Their ends are connected to the loudspeaker 6, specifically to its coil 30. The supply voltage is present between switches S1 and S3, and switches S2 and S4 are each connected to ground potential.

[0046] For the voltage states control signal SA = +1 and control signal SB = 0, switches S1 and S4 are closed, while S2 and S3 are open (first switch position configuration). The differential signal D applied to loudspeaker 6, in particular to coil 30, or the voltage applied to the coil, is as follows: D = S A − S B = 1 − 0 = + 1

[0047] For the voltage states control signal SA = 0 and control signal SB = +1, switches S2 and S3 are closed, while S1 and S4 are open (second switch position configuration). The differential signal D applied to loudspeaker 6, in particular to coil 30, or the voltage applied to the coil, is as follows: D = S A − S B = 0 − 1 = − 1

[0048] By appropriately controlling switches S1-S4, the following are achieved: FIG 2 The pulse sequences shown are retained. The H-bridge is simply switched between the two switch position configurations described above.

[0049] The principle described here, with its specially designed control signals SA and SB, is not limited to the application example described here with the Pinna microphone 12 and the RIC hearing aid. As an alternative to the Pinna microphone 12, the second component could be, for example, an analog sensor, such as a temperature sensor or a pressure sensor. Instead of an RIC hearing aid, it could also be other types of hearing aids, such as a BTE (Behind The Ear) hearing aid. Reference symbol list

[0050] 2 Hearing aid 4 Signal processing unit 6 Speaker 8 Amplifier section 10 Control line 10'A, 10B Interference line 12 Pina microphone 14 Power 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 SA, SB Control signal S sum Sum signal A Analog signal D Difference signal C Common mode signal

Claims

1. A method for operating a hearing aid (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 controlled by the signal processing unit (4) via two electrical conductors, each designated as an interference line (10A, 10B), and the second electrical component is connected to an electrical connection line, designated as a receiver line (12), wherein, during operation, a digital control signal (S A , S B ) is transferred, characterized in that the two control signals (S A , S B ) are modulated in such a way that a difference signal (D) of the two control signals (SA , S B ) is designed as a bipolar control signal, which alternates between exactly two voltage values ​​and that one of the two control signals (S A , S B ) formed common mode signal (C) is constant.

2. Method according to the preceding claim, wherein the bipolar control signal alternates between the voltage values ​​+1 and -1.

3. Method according to one of the preceding claims, in which the control signals (S A , S B ) are in antiphase, so that one control signal (S A ) the voltage value +1 and the other control signal (S B ) has a voltage value of 0.

4. Method according to one of the preceding claims, wherein the receiver line (12) is a single-end line.

5. Method according to one of the preceding claims, wherein the second component is an analog component which feeds an analog signal into the receiver line (12).

6. Method according to one of the preceding claims, wherein the second component is a microphone, in particular a pinna microphone (12).

7. Method according to one of the preceding claims, wherein the second component is an analog sensor.

8. Method according to one of the preceding claims, wherein the second component is connected via the receiver line (12) to an analog-digital converter (24) of the signal processing unit (4).

9. 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.

10. Method according to one of the preceding claims, in which the two line wires are routed together with the receiver line (12) and the hearing aid (2) is in particular a RIC hearing aid (2).

11. Hearing device (2), in particular a hearing aid device with - 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 conductors, each referred to as an interference line (10A, 10B), and - the signal processing unit (4) is designed to transmit a control signal (S A , S B) to the first component, - and wherein the second electrical component is connected to an electrical connection line referred to as the receiver line (12), characterized in that - the signal processing unit (4) is designed so that the control signals (S A , S B ) are modulated in such a way that a difference signal of the two control signals (S A , S B ) is designed as a bipolar control signal, which alternates between exactly two voltage values ​​and that one of the two control signals (S A , S B ) formed common mode signal is constant.

12. Hearing aid (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), - the signal processing unit (4) is arranged such that the two control signals (S A , S B ) are in antiphase, so that one control signal has the voltage value +1 and the other control signal has the voltage value 0, - the signal processing unit (4) is set up such that the bipolar control signal alternates 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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