Patent Description:
A cochlear implant system is a hearing prosthesis for deaf people whose auditory nerve is still functionally, as well as for highly hearing-impaired people for whom a conventional hearing aid does not provide sufficient audio perception. The general principle of a cochlear implant system is to bypass the normal acoustic hearing process and to replace it with electric signals which directly stimulate the cochlear nerve. For this purpose, a cochlear implant system generally comprises two main components: a sound processor unit and an implant unit. The sound processor unit may be worn behind the ear or alternatively attached to clothing, for example. It may comprise microphones, a power supply, electronics and a sound processor antenna with a first magnet. The implant unit may comprise an implant unit antenna with a second magnet, electronics and an array of electrodes. It is surgically implanted such that the implant unit antenna is placed under the skin in the vicinity of the ear and the array of electrodes is placed in the cochlea to stimulate the cochlear nerve. By means of the magnets, the sound processor antenna of the sound processor unit adheres on the skin above the implant unit antenna of the implant unit. Both the power supply of the implant unit and the signal transmission between the sound processor unit and the implant unit happen transcutaneously, i.e. penetrating the skin, by means of electromagnetic induction. For this purpose, an inductive link may be established between the sound processor antenna and the implant unit antenna. For signal transmission, the technique of modulation can be used, where a carrier signal with a carrier frequency is modulated by the information signal to be transmitted.

A problem with cochlear implant systems of prior art, such as illustrated in <CIT> and international patent application no. <CIT>, is that it is difficult to adjust the sound processor unit for optimal audio perception by the user. This is because the mutual inductance of the sound processor antenna and the implant unit antenna is not universally constant. For example, the mutual inductance may vary because of different skin thicknesses of different users, different magnetic strengths, antenna misalignment, different lengths of antenna cords, or different power required by the user. The varying mutual inductance typically leads to the user having to select, from a set of sound processor antennas, a suitable sound processor antenna that matches their skin thickness. Furthermore, it can lead to disturbed communication between the sound processor unit and the implant unit, or complex algorithms having to be performed by the electronics to find the correct configuration for the user.

In addition, even when a suitable sound processor antenna has been selected, it is hard to optimise the inductive link between the sound processor antenna and the implant antenna for all conditions. This is because the conditions which the inductive link has to conform to may vary, for example due to varying skin thickness, different magnetic strengths, antenna misalignment, different lengths of antenna cords, or different power required by the user. Usually, a compromise for operating the inductive link must be found between efficiency of power transfer, complexity, cost, reliability and usability.

Another problem with cochlear implant systems of prior art is that the sound processor antenna may be disconnected from the sound processor unit, for example to replace the sound processor antenna by a different sound processor antenna. Therefore, when a connection between a sound processor antenna and the sound processor unit has been established, it is often required to quickly determine characteristics of the sound processor antenna, for example in order to establish the inductive link between the sound processor antenna and an implant antenna. In addition, it is desired to detect a state where no sound processor antenna is connected to the sound processor unit, for example in order to save power by putting the sound processor unit or components of the sound processor unit into a stand-by mode.

Therefore, there is a need to provide a solution that addresses at least some of the above-mentioned problems. The present disclosure provides at least an alternative to the prior art.

A sound processor unit of a cochlear implant system according to the invention includes the features defined in claim <NUM>.

The sound processor unit comprises an electric circuit, which comprises a sound processor antenna with a sound processor antenna capacitance and a sound processor antenna inductance. The sound processor antenna of the sound processor unit with the sound processor antenna capacitance and the sound processor antenna inductance allows the sound processor unit to transmit and/or receive signals, for example to and/or from an implant unit which may be inductively linked to the sound processor unit, as well as to transfer electric power to the inductively linked implant unit.

The sound processor antenna capacitance and the sound processor antenna inductance are connected in series and form a resonant circuit. This allows the sound processor antenna to emit and/or absorb electromagnetic waves for transmitting and/or receiving signals, as well as to transfer electric power.

The electric circuit of the sound processor unit further comprises a switching element connected in series with the sound processor antenna capacitance and the sound processor antenna inductance. The electric circuit of the sound processor unit further comprises an inductive element connected in parallel with the switching element. When the switching element is in a closed state, the inductive element is in a short-circuited state and the sound processor antenna has a first resonant frequency. When the switching element is in an open state, the inductive element is in a non-short-circuited state and the sound processor antenna has a second resonant frequency which differs from the first resonant frequency. In this context, the closed state of the switching element is to be understood as a state in which an electric current flow over the switching element is enabled. The open state of the switching element is to be understood as a state in which an electric current flow over the switching element is interrupted.

By transitioning the switching element between the closed state and the open state, it is therefore possible, with the inductive element switching correspondingly between the short-circuited state and the non-short-circuited state, to switch the resonant frequency of the sound processor antenna between the first and the second resonance frequency. This allows the same type of sound processor unit to adapt to different resonant frequencies of an implant unit, for example. More specifically, an implant unit may have an implant antenna with a first resonant frequency that may be used when the skin thickness of the user is within a first interval, for example <NUM> to <NUM>. The implant antenna may have a second resonant frequency that may be used when the skin thickness is within a second interval, for example above <NUM>. By the sound processor unit being able to switch the resonant frequency of the sound processor antenna between the first and the second resonant frequency of the implant antenna, it is possible that the sound processor unit can establish an inductive link using different resonance frequencies corresponding to different skin thicknesses without having to exchange the sound processor antenna or the implant antenna. The user then no longer has to select a suitable sound processor antenna that matches their skin thickness from a set of sound processor antennas, such that user convenience is improved.

The switching element may comprise at least two transistors for short circuiting the inductive element. Thereby, a cost-effective, yet reliable switching element can be provided without numerous electronic components being required. However, a minimum of two transistors are needed as the current flowing through the transistors is sinusoidal and flows in both directions (quadratic behaviour).

The switching element may comprise at least a third transistor for controlling the at least two transistors that are used to short circuit the inductive element. Thereby, it is possible to simultaneously control the at least two transistors that can short circuit the inductive element.

The transistors of the switching element may be MOS transistors. By using MOS transistors for the switching element, the high space requirements of cochlear implant systems can be fulfilled better than for example with bipolar transistors, which is due to the MOS transistors being more suitable for miniaturisation. Furthermore, MOS transistors are advantageous in that they are easy to control due to their saturation state and in that they have a low power loss.

The switching element may comprise a DC voltage supply, a first NMOS transistor, a second NMOS transistor, a PMOS transistor, a first resistor and a second resistor. The DC voltage supply may comprise a positive terminal and a negative terminal. The first and second NMOS transistor and the PMOS transistor may comprise in each case a gate connection, a source connection and a drain connection. The first and second resistor may comprise in each case a first end connection and a second end connection. The negative terminal of the DC voltage supply may be electrically conductively connected to ground. The positive terminal of the DC voltage supply may be electrically conductively connected to the source connection of the PMOS transistor. The drain connection of the PMOS transistor may be electrically conductively connected to the first end connection of the first resistor, to the first end connection of the second resistor, to the gate connection of the first NMOS transistor, and to the gate connection of the second NMOS transistor. The source connection of the first NMOS transistor may be electrically conductively connected to the source connection of the second NMOS transistor. The second end connection of the first resistor may be electrically conductively connected to the drain connection of the first NMOS transistor. The second end connection of the second resistor may be electrically conductively connected to the drain connection of the second NMOS transistor. The switching element comprising a DC voltage supply, a first NMOS transistor, a second NMOS transistor, a PMOS transistor, a first resistor and a second resistor, which are electrically conductively connected to one another and to ground as explained above, may be a particularly advantageous realization. More specifically, the switching element is adapted to a sinusoidal wave form of the current and easily controllable from a digital sound processor of the sound processor unit, which may be electrically conductively connected to the gate connection of the PMOS transistor. In addition, due to the low power loss components being used in the switching element, the power consumption is low.

An amplifier may be used to drive the sound processor antenna. In particular, a class E amplifier or a class C amplifier may be used to drive the sound processor antenna. Both specified amplifier types have the advantage of being highly efficient. However, neither the switching element nor the inductive element lead to a limitation regarding the amplifier type used.

A method for switching a resonant frequency of a sound processor in a sound processor unit of a cochlear implant system according to the invention includes the features defined in claim <NUM>.

As already explained above in the context of the sound processor unit according the invention, by transitioning the switching element between the closed state and the open state, it is possible to switch the resonant frequency of the sound processor antenna between the first and the second resonance frequency. This allows the same type of sound processor unit to adapt to different resonant frequencies of an implant unit without having to exchange the sound processor antenna, for example. A user then no longer has to select a suitable sound processor antenna that matches their skin thickness from a set of sound processor antennas, such that user convenience is improved.

The transitioning of the switching element from the closed state to the open state or from the open state to the closed state may be caused or triggered by a processor, in particular a digital sound processor, of the electric circuit. The transitioning may be caused or triggered automatically by the processor. Thereby, user convenience can be improved further, since an action of the user is not necessary. The transitioning may also be caused or triggered by the processor in response to user input. This may give the user the possibility to influence the operation of the cochlear implant system according to their needs.

Within the present invention, a cochlear implant system is disclosed, too. The cochlear implant system comprises a sound processor unit as described above. By using a sound processor unit as described above, a cochlear implant system that is improved as described above can be provided.

The electronic hardware may include micro-electronic-mechanical systems (MEMS), integrated circuits (e.g. application specific), microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, printed circuit boards (PCB) (e.g. flexible PCBs), and other suitable hardware configured to perform the various functionality described throughout this disclosure, e.g. sensors, e.g. for sensing and/or registering physical properties of the environment, the device, the user, etc. Computer program shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

A hearing device (or hearing instrument, hearing assistance device) may be or include a hearing aid that is adapted to improve or augment the hearing capability of a user by receiving an acoustic signal from a user's surroundings, generating a corresponding audio signal, possibly modifying the audio signal and providing the possibly modified audio signal as an audible signal to at least one of the user's ears. 'Improving or augmenting the hearing capability of a user' may include compensating for an individual user's specific hearing loss. The "hearing device" may further refer to a device such as a hearable, an earphone or a headset adapted to receive an audio signal electronically, possibly modifying the audio signal and providing the possibly modified audio signals as an audible signal to at least one of the user's ears. Such audible signals may be provided in the form of an acoustic signal radiated into the user's outer ear, or an acoustic signal transferred as mechanical vibrations to the user's inner ears through bone structure of the user's head and/or through parts of the middle ear of the user or electric signals transferred directly or indirectly to the cochlear nerve and/or to the auditory cortex of the user.

A "hearing system" refers to a system comprising one or two hearing devices, and a "binaural hearing system" or a bimodal hearing system refers to a system comprising two hearing devices where the devices are adapted to cooperatively provide audible signals to both of the user's ears either by acoustic stimulation only, acoustic and mechanical stimulation, mechanical stimulation only, acoustic and electrical stimulation, mechanical and electrical stimulation or only electrical stimulation. The hearing system, the binaural hearing system or the bimodal hearing system may further include one or more auxiliary device(s) that communicates with at least one hearing device, the auxiliary device affecting the operation of the hearing devices and/or benefitting from the functioning of the hearing devices. A wired or wireless communication link between the at least one hearing device and the auxiliary device is established that allows for exchanging information (e.g. control and status signals, possibly audio signals) between the at least one hearing device and the auxiliary device. Such auxiliary devices may include at least one of a remote control, a remote microphone, an audio gateway device, a wireless communication device, e.g. a mobile phone (such as a smartphone) or a tablet or another device, e.g. comprising a graphical interface, a public-address system, a car audio system or a music player, or a combination thereof. The audio gateway may be adapted to receive a multitude of audio signals such as from an entertainment device like a TV or a music player, a telephone apparatus like a mobile telephone or a computer, e.g. a PC. The auxiliary device may further be adapted to (e.g. allow a user to) select and/or combine an appropriate one of the received audio signals (or combination of signals) for transmission to the at least one hearing device. The remote control is adapted to control functionality and/or operation of the at least one hearing device. The function of the remote control may be implemented in a smartphone or other (e.g. portable) electronic device, the smartphone / electronic device possibly running an application (APP) that controls functionality of the at least one hearing device.

In general, a hearing device includes i) an input unit such as a microphone for receiving an acoustic signal from a user's surroundings and providing a corresponding input audio signal, and/or ii) a receiving unit for electronically receiving an input audio signal. The hearing device further includes a signal processing unit for processing the input audio signal and an output unit for providing an audible signal to the user in dependence on the processed audio signal.

The input unit may include multiple input microphones, e.g. for providing direction-dependent audio signal processing. Such directional microphone system is adapted to (relatively) enhance a target acoustic source among a multitude of acoustic sources in the user's environment and/or to attenuate other sources (e.g. noise). In one aspect, the directional system is adapted to detect (such as adaptively detect) from which direction a particular part of the microphone signal originates. This may be achieved by using conventionally known methods. The signal processing unit may include an amplifier that is adapted to apply a frequency dependent gain to the input audio signal. The signal processing unit may further be adapted to provide other relevant functionality such as compression, noise reduction, etc. The output unit may include an output transducer such as a loudspeaker/receiver for providing an air-borne acoustic signal to the ear of the user, a mechanical stimulation applied transcutaneously or percutaneously to the skull bone, an electrical stimulation applied to auditory nerve fibers of a cochlea of the user. In some hearing devices, the output unit may include one or more output electrodes for providing the electrical stimulations such as in a cochlear implant, or the output unit may include one or more vibrators for providing the mechanical stimulation to the skull bone.

A cochlear implant system typically includes i) an external part for picking up and processing sound from the environment, and for determining sequences of pulses for stimulation of the electrodes in dependence on the sound from the environment, ii) a (typically wireless, e.g. inductive) transcutaneous communication link for transmitting information about the stimulation sequences and/or for transferring energy to iii) an implanted part allowing the stimulation to be generated and applied to a number of electrodes, which are implantable in different locations of the cochlea allowing a stimulation of different frequencies of the audible range. Such systems are e.g. described in <CIT> and in <CIT>.

In an aspect, the hearing device comprises multi-electrode array e.g. in the form of a carrier comprising a multitude of electrodes adapted for being located in the cochlea in proximity of an auditory nerve of the user. The carrier is preferably made of a flexible material to allow proper positioning of the electrodes in the cochlea such that the electrodes may be inserted in cochlea of a recipient. Preferably, the individual electrodes are spatially distributed along the length of the carrier to provide a corresponding spatial distribution along the cochlear nerve in cochlea when the carrier is inserted in cochlea.

Now referring to <FIG>, a schematic circuit diagram of an electric circuit of a sound processor unit according to the invention and a schematic circuit diagram of an electric circuit of an implant unit is shown. The electric circuit (<NUM>) of the sound processor unit comprises a sound processor antenna (<NUM>) with a sound processor antenna capacitance (<NUM>) and a sound processor antenna inductance (<NUM>). The sound processor antenna capacitance (<NUM>) and the sound processor antenna inductance (<NUM>) are connected in series and form a resonant circuit (<NUM>).

As shown in <FIG>, the sound processor antenna (<NUM>) of the sound processor unit with the sound processor antenna capacitance (<NUM>) and the sound processor antenna inductance (<NUM>) allows the sound processor unit to transmit and/or receive signals to and/or from an implant unit which is inductively linked to the sound processor unit, as well as to transfer electric power to the inductively linked implant unit. In <FIG>, a schematic circuit diagram of an electric circuit (<NUM>) of an implant unit is shown, too. The electric circuit (<NUM>) of the implant unit comprises an implant antenna (<NUM>) with an implant antenna capacitance (<NUM>) and an implant antenna inductance (<NUM>). The implant antenna capacitance (<NUM>) and the implant antenna inductance (<NUM>) are likewise connected in series and form a resonant circuit (<NUM>). Furthermore, the electric circuit (<NUM>) of the implant unit comprises an electric load, which is schematically represented by the resistance (<NUM>). As shown in <FIG>, the inductive link between the sound processor unit and the implant unit is established transcutaneously, i.e. penetrating the skin of the user.

The electric circuit (<NUM>) of the sound processor unit further comprises a switching element (<NUM>) connected in series with the sound processor antenna capacitance (<NUM>) and the sound processor antenna inductance (<NUM>). The electric circuit (<NUM>) of the sound processor unit further comprises an inductive element (<NUM>) connected in parallel with the switching element (<NUM>). As <FIG> shows, when the switching element (<NUM>) is in a closed state. electric current flow over the switching element (<NUM>) is enabled, and therefore the inductive element (<NUM>) is in a short-circuited state. The resonant circuit (<NUM>) of the sound processor antenna (<NUM>) is then formed by the sound processor antenna capacitance (<NUM>) and the sound processor antenna inductance (<NUM>). In this configuration, the sound processor antenna (<NUM>) has a first resonant frequency, which is not influenced by the inductive element (<NUM>). As <FIG> shows further, when the switching element (<NUM>) is in an open state, electric current flow over the switching element (<NUM>) is interrupted, and therefore the inductive element (<NUM>) is in a non-short-circuited state. The resonant circuit (<NUM>) of the sound processor antenna (<NUM>) is then formed by the sound processor antenna capacitance (<NUM>), the sound processor antenna inductance (<NUM>) and the inductive element (<NUM>). In this configuration, the sound processor antenna (<NUM>) has a second resonant frequency, which is influenced by the inductive element (<NUM>) and therefore differs from the first resonant frequency.

By transitioning the switching element (<NUM>) between the closed state and the open state, it is possible to switch the resonant frequency of the sound processor antenna (<NUM>) between the first and the second resonance frequency. This allows the sound processor unit to adapt to different resonant frequencies of the implant unit, which correspond to different skin thicknesses of a user, without having to exchange the sound processor antenna (<NUM>). The user then no longer has to select a suitable sound processor antenna that matches their skin thickness from a set of sound processor antennas, such that user convenience is improved.

The switching element (<NUM>) shown in <FIG> comprises two transistors (<NUM>, <NUM>) for short circuiting the inductive element (<NUM>). Thereby, a cost-effective, yet reliable switching element (<NUM>) can be provided without numerous electronic components being required. However, a minimum of two transistors (<NUM>, <NUM>) are needed as the current flowing through the transistors (<NUM>, <NUM>) is sinusoidal and flows in both directions (quadratic behaviour). Furthermore, the switching element (<NUM>) comprises a third transistor (<NUM>) for controlling the two transistors (<NUM>, <NUM>) that are used to short circuit the inductive element (<NUM>). Thereby, it is possible to simultaneously control the at least two transistors (<NUM>, <NUM>) that can short circuit the inductive element (<NUM>). The transistors (<NUM>, <NUM>, <NUM>) of the switching element (<NUM>) are MOS transistors, which meet the high space requirements of cochlear implant systems and are advantageous in that they are easy to control due to their saturation state and in that they have a low power loss.

More specifically, the switching element (<NUM>) shown in <FIG> comprises a first NMOS transistor (<NUM>) and a second NMOS transistor (<NUM>) for short circuiting the inductive element (<NUM>), as well as a PMOS transistor (<NUM>) for controlling the two NMOS transistors (<NUM>, <NUM>). Furthermore, the switching element (<NUM>) comprises a DC voltage supply (<NUM>), a first resistor (<NUM>) and a second resistor (<NUM>). The DC voltage supply (<NUM>) comprises a positive terminal and a negative terminal. The first and second NMOS transistor (<NUM>, <NUM>) and the PMOS transistor (<NUM>) comprise in each case a gate connection, a source connection and a drain connection. The first and second resistor (<NUM>, <NUM>) comprise in each case a first end connection and a second end connection. The negative terminal of the DC voltage supply (<NUM>) is electrically conductively connected to ground. The positive terminal of the DC voltage supply (<NUM>) is electrically conductively connected to the source connection of the PMOS transistor (<NUM>). The drain connection of the PMOS transistor (<NUM>) is electrically conductively connected to the first end connection of the first resistor (<NUM>), to the first end connection of the second resistor (<NUM>), to the gate connection of the first NMOS transistor (<NUM>), and to the gate connection of the second NMOS transistor (<NUM>). The source connection of the first NMOS transistor (<NUM>) is electrically conductively connected to the source connection of the second NMOS transistor (<NUM>). The second end connection of the first resistor (<NUM>) is electrically conductively connected to the drain connection of the first NMOS transistor (<NUM>). The second end connection of the second resistor (<NUM>) is electrically conductively connected to the drain connection of the second NMOS transistor (<NUM>). The switching element (<NUM>) comprising a DC voltage supply (<NUM>), a first NMOS transistor (<NUM>), a second NMOS transistor (<NUM>), a PMOS transistor (<NUM>), a first resistor (<NUM>) and a second resistor (<NUM>), which are electrically conductively connected to one another and to ground as explained above, is a particularly advantageous realization with respect to the adaptation to a sinusoidal wave form of the current, with respect to easy control from a digital sound processor of the sound processor unit, and with respect to low power consumption.

The transitioning of the switching element (<NUM>) from the closed state to the open state or from the open state to the closed state is caused or triggered here by a digital sound processor of the electric circuit (<NUM>). As <FIG> shows, the digital sound processor is electrically conductively connected to the gate connection of the PMOS transistor (<NUM>). Here, the transitioning is caused or triggered by the processor in response to user input, which gives the user the possibility to influence the operation of the cochlear implant system according to their needs. However, an automatic causing or triggering the transitioning by the digital sound processor is likewise conceivable.

As shown in <FIG>, a class E amplifier (<NUM>) is used to drive the sound processor antenna (<NUM>). The class E amplifier (<NUM>) has the advantage of being highly efficient. However, neither the switching element nor the inductive element lead to a limitation regarding the amplifier type used and therefore, other amplifier types are also conceivable.

<FIG> shows a schematic circuit diagram of an electric circuit of a sound processor unit according to the first and second illustrative examples not being part of the claimed invention and a schematic circuit diagram of an electric circuit of an implant unit. With respect to the first illustrative example, the electric circuit (<NUM>) of the sound processor unit comprises a variable oscillator configured to generate an adjustable carrier frequency of an inductive link (<NUM>) between the sound processor unit and the implant unit. In <FIG>, the variable oscillator is integrated into a digital sound processor (<NUM>) of the sound processor unit, and a voltage source (<NUM>) is used to supply electric power to the digital sound processor (<NUM>) including the variable oscillator. The electric circuit (<NUM>) of the implant unit is shown only schematically and comprises an implant antenna (<NUM>) as well as an electric load (<NUM>) and a modulator (<NUM>).

The variable oscillator integrated into the digital sound processor (<NUM>) is used for generating a carrier frequency of the inductive link (<NUM>), with a frequency adjustment of the variable oscillator leading to an adjustment of the carrier frequency. In more detail, the variable oscillator generates an alternating voltage which is in addition modulated by a signal voltage of a signal to be transmitted. However, the modulation is not mandatory, and an unmodulated alternating voltage is also conceivable. In the example of <FIG>, the modulated alternating voltage is fed into the sound processor antenna (<NUM>) of the sound processor unit, where it causes a corresponding electric current such that the sound processor antenna (<NUM>) irradiates corresponding electromagnetic waves. Like this, the alternating voltage generated by the variable oscillator acts as a carrier frequency of the inductive link (<NUM>) between the sound processor antenna (<NUM>) and the implant antenna (<NUM>). When the alternating voltage of the variable oscillator is adjusted, the carrier frequency is adjusted accordingly. Here, the variable oscillator is controlled, i.e. caused or triggered to adjust the generated alternating voltage, by the digital sound processor (<NUM>) of the sound processor unit, into which it is integrated.

With the variable oscillator being configured to generate an adjustable carrier frequency of the inductive link (<NUM>), it is possible to adjust the carrier frequency in real time. This enables a quick and simple optimisation of the inductive link (<NUM>) in case of varying mutual inductance such that both an improved power transmission and an improved communication between the sound processor unit and the implant unit can be provided. In addition, the adjustment of the carrier frequency can be realised with low power consumption and has no impact on the modulation used for communicating with the implant unit. Furthermore, it allows the same type of sound processor unit to adapt to different types of implant units, which have different implant antennas with different resonant frequencies, without having to exchange the sound processor antenna (<NUM>). A user then no longer has to select a suitable sound processor antenna that matches their skin thickness from a set of sound processor antennas, such that user convenience is improved.

Furthermore, as shown in <FIG>, an amplifier is used to drive the sound processor antenna (<NUM>). Here, a class D amplifier is used, which is likewise integrated into the digital sound processor (<NUM>). However, the variable oscillator configured to generate an adjustable carrier frequency of the inductive link (<NUM>) does not lead to a limitation regarding the amplifier type used and therefore, other amplifier types are also conceivable.

<FIG> shows a schematic flow diagram illustrating operations performed in accordance with a method according to the first illustrative example not being part of the claimed invention. According to this example, the method (<NUM>) for adjusting the carrier frequency of an inductive link between a sound processor unit and an implant unit of a cochlear implant system comprises: - generating (<NUM>) electromagnetic waves using a variable oscillator, wherein the frequency of the electromagnetic waves is varied over time between a lower limit frequency and an upper limit frequency;.

Although the different elements are arranged in a particular order in the flow diagram of <FIG>, any reasonable way of performing the method, which is known to a person skilled in the art, and which may likewise result in a different order or no order at all, i.e. the different elements being for example performed simultaneously, is conceivable. In particular, generating (<NUM>) electromagnetic waves and measuring (<NUM>) at least one parameter are performed simultaneously in the method of <FIG>.

The method of <FIG> allows to identify and set a suitable carrier frequency for the inductive link in a quick and simple way. This enables optimised operation of the inductive link, for example with respect to power consumption or reliability of communication between the sound processor unit and the implant unit.

The sound processor unit according to the first and second illustrative example, which has been explained above in the context of <FIG>, is configured to perform a method according to the first illustrative example, in particular the method of <FIG>. For this purpose, the sound processor unit comprises means (<NUM>, <NUM>) for generating electromagnetic waves, wherein the frequency of the electromagnetic waves is variable. These means for generating electromagnetic waves involve the variable oscillator integrated into the digital sound processor (<NUM>), the sound processor antenna (<NUM>), as well as the digital sound processor (<NUM>) that controls the variable oscillator. The sound processor unit further comprises means (<NUM>, <NUM>, <NUM>, <NUM>) for measuring at least one parameter related to the cochlear implant system. These means for measuring involve a coupled inductance (<NUM>), a rectifier (<NUM>), an analog-digital-converter (<NUM>) and a demodulator (<NUM>). The sound processor unit further comprises means (<NUM>) for selecting a frequency, which is in this case the digital sound processor (<NUM>). The sound processor unit further comprises means (<NUM>) for using the selected frequency as a carrier frequency for the inductive link (<NUM>), which involve the variable oscillator integrated into the digital sound processor (<NUM>) and the digital sound processor (<NUM>) that controls the variable oscillator.

In the particular method of <FIG>, when this method is performed by the sound processor unit of <FIG>, the variable oscillator used for generating (<NUM>) the electromagnetic waves is the variable oscillator which is integrated into the digital sound processor (<NUM>), and which is used for generating the adjustable carrier frequency of the inductive link (<NUM>). However, it is also conceivable that the variable oscillator used for generating (<NUM>) the electromagnetic waves is a different variable oscillator, the generated alternating voltage of which is likewise fed into the sound processor antenna (<NUM>).

Furthermore, in the method of <FIG>, the at least one measured parameter is the amplitude of a response signal from the implant antenna (<NUM>). For measuring this amplitude, the analog-digital-converter (<NUM>) is used in conjunction with the coupled inductance (<NUM>) and the rectifier (<NUM>). However, the coupled inductance (<NUM>) and the rectifier (<NUM>) may be omitted if other parameters are measured as the at least one parameter related to the cochlear implant system. Measuring the amplitude of a response signal from the implant antenna allows to adjust the carrier frequency such that the efficiency and reliability of the communication between the sound processor unit and the implant unit is optimised, and by using the analog-digital converter (<NUM>), the measurement results can easily be processed and evaluated by the digital sound processor (<NUM>) of the electric circuit. However, it is also conceivable that the at least one measured parameter is a parameter related to a demodulated response signal from the implant antenna. Regarding this, the means for measuring of the electric circuit (<NUM>) of the sound processor unit also involve a demodulator (<NUM>), which is used to measure the parameter related to a demodulated response signal from the implant antenna. In addition, the electric circuit (<NUM>) of the implant unit also comprises a modulator (<NUM>) to generate a modulated response signal. Measuring a parameter related to a demodulated response signal from the implant antenna also allows to adjust the carrier frequency such that the efficiency and reliability of the communication between the sound processor unit and the implant unit is optimised. Furthermore, it is also conceivable that the at least one measured parameter is the power consumption of the cochlear implant system. This allows to adjust the carrier frequency such that the power consumption of the cochlear implant system is minimised.

<FIG> shows a schematic flow diagram illustrating operations performed in accordance with an exemplary method according to the second illustrative example not being part of the claimed invention. According to this embodiment, the method (<NUM>) for determining at least one state and/or property related to a sound processor unit of a cochlear implant system comprises:.

Although the different elements are arranged in a particular order in the flow diagram of <FIG>, any reasonable way of performing the method, which is known to a person skilled in the art, and which may likewise result in a different order or no order at all, i.e. the different elements being for example performed simultaneously, is conceivable.

The method of <FIG> allows to obtain information about the state of operation of the sound processor unit of a cochlear implant system. This information can be used to optimise the operation. Furthermore, the method of <FIG> allows the information to be obtained particularly quickly.

<FIG> shows a schematic circuit diagram of an electric circuit of a sound processor unit according to the second illustrative example. More specifically, <FIG> shows a detailed view of the schematic circuit diagram of <FIG>, where only elements that are primarily relevant for the second illustrative example are shown in more detail and elements that are not primarily relevant for the second illustrative example are omitted. Nevertheless, a sound processor unit with an electric circuit comprising only the elements shown in <FIG> would function as a stand-alone sound processor unit according to the second illustrative example. With the electric circuit (<NUM>) shown in <FIG>, the sound processor unit is configured to perform a method according to the second illustrative example, in particular the method shown in <FIG>, and comprises means for performing such a method. More specifically, the electric circuit (<NUM>) comprises a digital sound processor (<NUM>), into which a class D amplifier with a general purpose input and output is integrated. As will be explained below, the digital sound processor (<NUM>) acts as:.

As shown in <FIG>, the digital sound processor (<NUM>) is electrically conductively connected to a voltage source, which supplies a charging control voltage (VCC). The digital sound processor (<NUM>) further comprises a first switch (<NUM>) and a second switch (<NUM>), which are both realised using MOS transistors and indicated only schematically in <FIG>. The digital sound processor (<NUM>) supplies the charging control voltage (VCC) to a first connection of the first and second switch (<NUM>, <NUM>) in each case, with an intermediate pullup resistor (<NUM>) being additionally integrated between the charging control voltage supply and the first connection in case of the first switch (<NUM>). In addition, the first and second switch (<NUM>, <NUM>) both comprise a second connection, which is electrically conductively connected to ground in each case. Furthermore, the first and second switch (<NUM>, <NUM>) of the digital sound processor (<NUM>) comprise in each case a third connection, which is electrically conductively connected in each case to the sound processor antenna (<NUM>) having a sound processor antenna capacitance (<NUM>) and a sound processor antenna inductance (<NUM>). The digital sound processor (<NUM>) further comprises a timer (<NUM>) and a comparator (<NUM>). Moreover, a class D amplifier (not shown in <FIG>) with a general purpose input and output is used to charge or at least attempt to charge the sound processor antenna (<NUM>), the class D amplifier being integrated into the sound processor unit (<NUM>), as explained above in the context of <FIG>. Using a class D amplifier has the advantage that the MOS transistors of the class D amplifier can be used as the general purpose input and output.

To perform the method shown in <FIG>, both switches (<NUM>, <NUM>) are initially applied to ground and thus, the antenna (<NUM>) is completely discharged. After a waiting time of <NUM> at maximum, both switches (<NUM>, <NUM>) are applied to the respective first connection that is connected, directly or via the pullup resistor (<NUM>), to the charging control voltage (VCC), and therefore, the antenna starts to be charged by means of the voltage source supplying the charging control voltage (VCC) and by means of the pullup resistor (<NUM>). Simultaneously, the timer (<NUM>) starts running and the digital sound processor (<NUM>) measures the charging voltage. Using the comparator (<NUM>), the charging voltage is compared to a predetermined threshold (VRef), which is here set to the value of the charging control voltage (VCC).

When the charging voltage exceeds the threshold (VRef), the timer (<NUM>) stops running. The time interval determined by the timer (<NUM>) is then equal to the rise time of the sound processor antenna (<NUM>), which is the difference between the end time, at which the charging voltage exceeded the predetermined threshold, and the start time, at which the charging was started. Based on the determined rise time, the digital sound processor (<NUM>) then determines at least one state and/or property related to the cochlear implant system. Here, the digital sound processor (<NUM>) determines that the sound processor antenna (<NUM>) is connected to the sound processor unit. In addition, it determines a resonant frequency and an antenna type of the sound processor antenna (<NUM>) based on the determined rise time.

If no sound processor antenna was connected to the sound processor unit, the digital sound processor (<NUM>), more specifically the class D amplifier integrated into the digital sound processor (<NUM>), would only attempt to charge a sound processor antenna of the sound processor unit. Nevertheless, the method shown in <FIG> could still be performed, and the digital sound processor (<NUM>) in this case could determine, based on the determined rise time, that no sound processor antenna is connected to the sound processor unit.

With reference to <FIG>, it is explained in the following how a resonant frequency and an antenna type of the sound processor antenna (<NUM>) are determined based on the determined rise time, or how it is determined, based on the determined rise time, that no sound processor antenna is connected to the sound processor unit. <FIG> shows exemplary charging voltage functions obtained by performing a method according to the second illustrative example not being part of the claimed invention. More specifically, a first charging voltage function obtained with a first type of sound processor antenna connected to a sound processor unit, a second charging voltage function obtained with a second type of sound processor antenna connected to a sound processor unit, and a third charging voltage function obtained with no sound processor antenna connected to a sound processor unit is shown. The individual charging voltage functions are referred to as "Antenna <NUM>", "Antenna <NUM>", and "No antenna" in <FIG>. As the figure shows, the rise times corresponding to the different charging functions differ from each other: The charging voltage function corresponding to no sound processor antenna being connected has the smallest rise time and the threshold (VCC) is exceeded the earliest. Moreover, the charging voltage function corresponding to the first type of sound processor antenna has a longer rise time than the charging voltage function corresponding to the second type of sound processor antenna. Therefore, as <FIG> shows, the rise time is characteristic for whether a sound processor antenna is connected to the sound processor unit or not, and characteristic for the type of sound processor antenna. This correlation is used by the digital sound processor (<NUM>) of <FIG>: It comprises a memory (<NUM>) with a database, in which different rise times are associated with different sound processor antenna types and their corresponding resonant frequency. The database also comprises the rise time corresponding to no sound processor antenna being connected to the sound processor unit. Then, by comparing the determined rise time with the rise times in the database, the digital sound processor (<NUM>) is able to determine, whether or not a sound processor antenna is connected to the sound processor unit, and to determine a resonant frequency and an antenna type of the sound processor antenna.

Determining whether or not a sound processor antenna is connected to the sound processor unit, and determining a resonant frequency of the sound processor antenna and a type of the sound processor antenna allows to optimise the operation of the cochlear implant system accordingly. For example, the sound processor unit or components of the sound processor unit may be deactivated if it is determined that no sound processor antenna is connected to the sound processor unit, or the sound processor unit or components of the sound processor unit may be activated or re-activated if it is determined that a sound processor antenna is connected to the sound processor unit. In addition, an inductive link between the sound processor antenna and an implant antenna of an implant unit of the cochlear implant system can be optimised with respect to the sound processor antenna if its type and/or resonant frequency are known.

The digital sound processor (<NUM>) shown in <FIG> performs the method shown in <FIG> during a booting process of the cochlear implant system, and after initiation by manual user input. This allows to determine whether or not a sound processor antenna is connected to the sound processor unit, and to determine at least one property related to the sound processor antenna, right after the cochlear implant system is switched on and starts its operation, and in case of an establishment or re-establishment of a connection between the sound processor unit and a sound processor antenna by a user.

After performing the method shown in <FIG> to determine the resonant frequency and antenna type of the sound processor antenna, the digital sound processor (<NUM>) of the sound processor unit uses the obtained resonant frequency to optimise the operation of the cochlear implant system, as will be explained below with reference to <FIG> and <FIG>. At first, determining a resonant frequency of the sound processor antenna based on the determined antenna type would be conceivable. However, this is omitted here, since a resonant frequency of the sound processor antenna has already been determined based on the determined rise time. Instead, the resonant frequency of the sound processor antenna, which has been determined based on the determined rise time, is used as a carrier frequency for an inductive link (<NUM>) between the sound processor unit and an implant unit (cf. <FIG>) of the cochlear implant system. For this purpose, the variable oscillator is used, which is integrated into the digital sound processor (<NUM>), as described above in the context of <FIG>. The digital sound processor (<NUM>) controls the variable oscillator, which feeds the sound processor antenna (<NUM>), such that the determined resonant frequency of the sound processor antenna (<NUM>) is used as a carrier frequency for the inductive link (<NUM>). Furthermore, the digital sound processor (<NUM>) causes or triggers a method according to the first illustrative example to be performed, as explained above in the context of <FIG>, in order to adjust the carrier frequency of the inductive link (<NUM>). Here, the lower and upper limit frequency for the method according to the first illustrative example are selected such that the lower and upper limit frequency form a frequency interval which includes the determined resonant frequency of the sound processor antenna (<NUM>). Thereby, optimised operation of the inductive link, for example with respect to power consumption or reliability of communication between the sound processor unit and the implant unit, is achieved. Overall, the operation of the cochlear implant system is optimised.

Referring now to <FIG>, a schematic illustration of a cochlear implant system according to the first and second illustrative example is shown. The cochlear implant system (<NUM>) comprises an implant unit (<NUM>) with an implant antenna (<NUM>) and a sound processor unit (<NUM>) with a sound processor antenna (<NUM>). The sound processor unit (<NUM>) combines the features of a sound processor unit according to the invention, a sound processor unit according to the first illustrative example, and a sound processor unit according to the second illustrative example. Thereby, an improved cochlear implant system which combines the advantages of all three aspects is provided.

A computer program (product) comprising instructions which, when the program is executed by a computer, cause the computer to carry out (steps of) the methods described above, in the 'detailed description of embodiments' and in the claims is furthermore provided by the present application.

In an aspect, the functions may be stored on or encoded as one or more instructions or code on a tangible computer-readable medium. The computer readable medium includes computer storage media adapted to store a computer program comprising program codes, which when run on a processing system causes the data processing system to perform at least some (such as a majority or all) of the steps of the method described above, in the and in the claims.

By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. In addition to being stored on a tangible medium, the computer program can also be transmitted via a transmission medium such as a wired or wireless link or a network, e.g. the Internet, and loaded into a data processing system for being executed at a location different from that of the tangible medium.

In an aspect, a data processing system comprising a processor adapted to execute the computer program for causing the processor to perform at least some (such as a majority or all) of the steps of the method described above and in the claims.

It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, but an intervening element may also be present, unless expressly stated otherwise. The steps of any disclosed method are not limited to the exact order stated herein, unless expressly stated otherwise.

Reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more.

Claim 1:
Sound processor unit of a cochlear implant system,
wherein the sound processor unit comprises an electric circuit (<NUM>), which comprises a sound processor antenna (<NUM>) with a sound processor antenna capacitance (<NUM>) and a sound processor antenna inductance (<NUM>),
wherein the sound processor antenna capacitance (<NUM>) and the sound processor antenna inductance (<NUM>) are connected in series and form a resonant circuit (<NUM>),
wherein the electric circuit (<NUM>) of the sound processor unit further comprises a switching element (<NUM>) connected in series with the sound processor antenna capacitance (<NUM>) and the sound processor antenna inductance (<NUM>), and the electric circuit (<NUM>) of the sound processor unit further comprises an inductive element (<NUM>) connected in parallel with the switching element (<NUM>),
wherein when the switching element (<NUM>) is in a closed state, the inductive element (<NUM>) is in a short-circuited state and the sound processor antenna (<NUM>) has a first resonant frequency, and when the switching element (<NUM>) is in an open state, the inductive element (<NUM>) is in a non-short-circuited state and the sound processor antenna (<NUM>) has a second resonant frequency which differs from the first resonant frequency.