Hearing aid with ear EEG recording
A hearing aid includes a plurality of electrode units, where each of the plurality of electrode units includes an electrode configured to provide an electrical stimulation to a user of the hearing aid and/or to measure a bio response signal of the user; a plurality of electrode channel circuits, where each of the plurality of electrode channel circuits includes: an operational amplifier comprising a first input terminal configured to receive the bio response signal and provide an amplified bio response signal, and the operational amplifier includes a first load input; a first DC offset unit configured to reduce the impact of DC offset in the electrode channel circuit of the plurality of electrode channel circuits by receiving a part of the amplified bio response signal and converting it to a feedback current signal which is transmitted to the first load input for providing balanced drain currents in the operational amplifier.
1 . A hearing aid comprising;
a plurality of electrodes, where each of the plurality of electrodes is configured to provide an electrical stimulation to a user of the hearing aid and/or to measure a bio response signal of the user;
a plurality of electrode channel circuits, where each of the plurality of electrode channel circuits includes:
an operational amplifier comprising a first input terminal configured to receive the bio response signal and provide an amplified bio response signal, and the operational amplifier includes a first load input;
a first DC offset unit configured to reduce the impact of DC offset in the electrode channel circuit of the plurality of electrode channel circuits by receiving a part of the amplified bio response signal and converting the received part of the amplified bio response signal to a feedback current signal which is transmitted to the first load input for providing balanced drain currents in the operational amplifier;
an analog-to digital converter wherein the amplified electrical response signal is converted to a digital electrical signal via the analog-to-digital converter;
wherein the first DC offset unit includes:
a controller configured to provide a control signal based on the digital-electrical signal,
an offset storage capacitor connected to the first input terminal of the operational amplifier or the first load input,
a pulse current source configured to increase or decrease in discrete steps a voltage level of the offset storage capacitor based on the control signal, and
wherein the offset storage capacitor is configured to maintain the voltage level at a level proportional to a DC offset voltage at the first input terminal or at the first load input for providing the balanced drain currents of the operational amplifier.
2 . A hearing aid according to claim 1 ,
wherein each of the plurality of electrode channel circuits includes a second DC offset unit configured to receive the bio response signal and reduce the impact of DC offset and forward the bio response signal, and
wherein the second DC offset unit includes a shunt impedance circuit including multiple shunt resistors and a voltmeter configured to measure an output voltage of an output of the second DC offset unit.
3 . A hearing aid according to claim 1 , wherein each of the plurality of electrode channel circuits includes an impedance matching circuit configured to receive the bio response signal and to match a first impedance of a first electrode of the plurality of electrodes to at least a second impedance of a second electrode of the plurality of electrodes.
4 . A hearing aid according to claim 3 , wherein the impedance matching circuit is configured to receive the bio response signal and forward the impedance matched bio response signal to the operational amplifier or to the second DC offset unit.
5 . A hearing aid according to claim 3 , wherein an alternating current, a direct current or a combination of an alternating current and a direct current is applied to an electrode of the plurality of electrodes via the impedance matching circuit of an electrode channel circuit of the plurality of electrode channel circuits, and where the electrode is configured to apply the electrical stimulation based on the current.
6 . A hearing aid according to claim 5 , wherein a second impedance matching circuit of a second electrode channel circuit of the plurality of electrode channel circuits is configured to measure a plurality of impedances of a second electrode of the plurality of electrodes, and based on the plurality of measured impedances both a resistive impedance and a capacitive impedance of the second electrode of the plurality of electrodes are determined in the second impedance matching circuit or in an impedance processor unit of the hearing aid.
7 . A hearing aid according to claim 1 , comprising an analog-to-digital converter, wherein the amplified bio response signal is converted to a digital electrical signal via an analog-to-digital converter, and the first DC offset unit further includes:
an offset correction circuit configured to receive the digital electrical signal and provide a digital offset correction signal based on a measure of a DC offset voltage in the digital electrical signal,
a digital-to-analog converter configured to receive the digital offset correction signal and convert it to the feedback current signal which is then transmitted to the first load input of the operational amplifier.
8 . A hearing aid according to claim 1 , wherein the controller is configured to determine the discrete steps by changing a magnitude and/or a duration of the current pulses provided by the pulse current source.
9 . A hearing aid according to claim 1 , wherein the pulsed current source is turned on and off based on an input from the controller, where a DC offset is detected or a DC offset that is above a DC offset threshold is detected by the controller, the pulsed current source is turned on, and where a DC offset is not detected or a DC offset that is below a DC offset threshold is detected by the controller, the pulsed current source is turned off.
10 . A hearing aid according to claim 2 , wherein the impedance matching circuit is configured to match the first impedance to the at least second impedance based on a first measured output voltage of a primary second DC offset unit connected to the first electrode and on a second measured output voltage of a secondary second DC offset unit connected to the second electrode.
11 . A hearing aid according to claim 1 , wherein the hearing aid is configured to compensate a hearing loss of a user of the hearing aid, comprising;
a microphone configured to receive an acoustic wave and provide an audio signal based on the acoustic wave,
a signal processor unit configured to process the audio signal and provide a processed audio signal;
an output transducer configured to output the processed audio signal to the user,
and wherein the signal processor unit is configured to process the audio signal based on the amplified bio response signal or is configured to adapt a hearing profile stored within a memory of the hearing aid based on the amplified bio response signal.
12 . A hearing aid according to claim 1 , comprising;
an in-the-ear unit;
a behind-the-ear unit;
a communication link configured to provide an electrical connection between the in-the-ear unit and the behind-the-ear unit,
a processor unit configured to receive the amplified bio response signal via the communication link, and
wherein one or more of the plurality of electrodes are arranged in the in-the-ear unit, and the processor unit is arranged in the behind-the-ear unit of the hearing aid.
13 . A hearing aid according to claim 12 , wherein the communication link is a communication bus or a wireless communication link.
14 . A hearing aid according to claim 1 , comprising a housing that includes the plurality of electrodes and the plurality of electrode channel circuits.
15 . A hearing aid according to claim 2 , wherein each of the plurality of electrode channel circuits includes an impedance matching unit circuit configured to receive the bio response signal and to match a first impedance of a first electrode of the plurality of electrodes to at least a second impedance of a second electrode of the plurality of electrodes.
16 . A hearing aid according to claim 3 , wherein the impedance matching circuit is configured to receive the bio response signal and forward the impedance matched bio response signal to the operational amplifier or to the second DC offset unit.
17 . A hearing aid comprising;
a plurality of electrode units, where each of the plurality of electrode units includes an electrode configured to provide an electrical stimulation to a user of the hearing aid and/or to measure a bio response signal of the user;
a plurality of electrode channel circuits, where each of the plurality of electrode channel circuits is connected to a re includes:
a DC offset unit configured to receive the bio response signal and reduce the impact of DC offset in the bio response signal and forward the bio response signal;
an operational amplifier comprising a first input terminal configured to receive the bio response signal forwarded by the and provide an amplified bio response signal, and the operational amplifier includes a first load input;
wherein each of the plurality of electrode channel circuits includes an impedance matching circuit configured to receive the bio response signal and to match a first impedance of a first electrode unit of the plurality of electrode units to at least a second impedance of a second electrode unit of the plurality of electrode units; and
wherein the DC offset unit of each electrode channel circuit includes a shunt impedance circuit including multiple shunt resistors and a voltmeter configured to measure an output voltage of an output of the DC offset unit, and
wherein the impedance matching circuit of each of the plurality of electrode channel circuits is configured to match the first impedance to the at least second impedance based on a first measured output voltage of the voltmeter of the DC offset unit of the corresponding electrode channel circuit and on a second measured output voltage of the voltmeter of the DC offset unit of another of the plurality of electrode channel circuits.
18 . A hearing aid according to claim 17 , further comprising:
another DC offset unit configured to reduce the impact of DC offset in the electrode channel circuit of the plurality of electrode channel circuits by receiving a part of the amplified bio response signal and converting the received part of the amplified bio response signal to a feedback current signal which is transmitted to the first load input for providing balanced drain currents in the operational amplifier; and
an analog-to-digital converter, wherein the amplified bio response signal is converted to a digital electrical signal via an analog-to-digital converter,
wherein the another DC offset unit includes:
an offset correction circuit configured to receive the digital electrical signal and provide a digital offset correction signal based on a measure of a DC offset voltage in the digital electrical signal,
a first digital-to-analog converter configured to receive the digital offset correction signal and convert it to the feedback current signal which is then transmitted to the first load input of the operational amplifier.