1. Field of the Invention
The present invention relates to partially or fully implantable hearing aids for rehabilitation of an inner ear hearing disorder, which have a microphone which delivers an audio signal, an electronic signal processing and amplification unit which is located in an audio signal processing electronic hearing aid path, an implantable electromechanical output converter and a unit for supplying power to the hearing aid.
2. Description of Related Art
Partially and fully implantable hearing aids for rehabilitation of inner ear damage with mechanical stimulation of the damaged inner ear have recently been available or will soon be available on the market journal HNO 46:844-852, 10-1998, H. P. Zenner et al., xe2x80x9cInitial implantations of a completely implantable electronic hearing system in patients with an inner ear hearing disorderxe2x80x9d; journal HNO 46:853-863, 10-1998,. Leysieffer et al., xe2x80x9cA completely implantable hearing system for inner ear hearing handicapped: TICA LZ 3001xe2x80x9d); U.S. Pat. Nos. 5,277,694; 5,788,711; 5,814,095; 5,554,096; and 5,624,376.
Especially in filly implantable systems is the visibility of the system not an issue, so that in addition to the advantages of high sound quality, the open auditory canal and full suitability for everyday use, high future patient acceptance can be assumed.
Many individuals suffer from intermittent or permanent tinnitus which cannot be cured by surgery and against which there have been no approved drug forms of treatment to date. Therefore, so-called tinnitus maskers are known (published PCT application WO-A-90/07251). They are small, battery-operated devices which are worn like a hearing aid behind or in the ear and they cover (mask) the tinnitus psychoacoustically by artificial sounds which are emitted, for example, via a hearing aid speaker into the auditory canal and which reduce the disturbing tinnitus as far as possible below the threshold of perception. The artificial sounds are often narrowband noise (for example, third octave noise) which in its spectral position and its loudness level can be adjusted via a programming device to enable the maximum possible adaptation to the individual tinnitus situation. Moreover, there has recently been devised the so-called xe2x80x9cretraining methodxe2x80x9d in which the perceptibility of the tinnitus is likewise supposed to be largely suppressed by a combination of a mental training program and presentation of broadband sound (noise) near the auditory threshold. These devices are also called xe2x80x9cnoisersxe2x80x9d journal xe2x80x9cHoerakustikxe2x80x9d 2/97, pages 26 and 27).
In the two aforementioned methods, technical devices similar to hearing aids can be visibly carried externally on the body in the area of the ear for treatment of tinnitus using hardware; they stigmatize the wearer and therefore are not willingly worn.
U.S. Pat. No. 5,795,287 discloses an implantable tinnitus masker with a direct driving of the middle ear, for example, via an electromechanical converter which is coupled to the ossicle chain. This directly coupled converter can preferably be a so-called xe2x80x9cfloating mass transducerxe2x80x9d (FMT). This FMT corresponds to the converter for implantable hearing aids which is known from U.S. Pat. No. 5,624,376. U.S. Pat. No. 5,795,287 clearly describe especially the xe2x80x9cdirect drivexe2x80x9d concept: this is defined explicitly as only the types of coupling to the inner ear for purposes of tinnitus masking which are of a mechanical nature, therefore direct mechanical converter couplings to one ossicle of the middle ear, such as, for example, by the FMT converter and also air gap-coupled electromagnetic converters such as is described, for example, in U.S. Pat. No. 5,105,225.
U.S. Pat. No. 5,795,287 describes solely implantable systems which are used for tinnitus masking and which are designed to mask the tinnitus based on direct mechanical stimulation of the inner ear with masking signal forms. But, since, as described above, inner ear noise very often occurs simultaneously with inoperable inner ear damage, for the wearer of the implant known from U.S. Pat. No. 5,795,287, technical and hardware measures must also be taken to rehabilitate the inner ear damage. This is only possible by additional application of a hearing aid of conventional design, i.e. a hearing aid worn outside on the body with acoustic stimulation of the eardrum. Especially here, neither a partially nor a fully implantable system is considered, since these systems, likewise, require mechanical coupling to a suitable middle ear structure for mechanical stimulation of the inner ear; one such simultaneous application of two different implants which must fundamentally deliver their actuator stimulus at the same destination is hardly feasible either surgically or technically; in addition, it entails other major clinical risks.
A primary object of this invention is to treat more easily and effectively the problems associated with the simultaneous occurrence of inner ear damage and tinnitus while avoiding the above described defects.
Proceeding from a partially or fully implantable hearing aid for rehabilitation of a inner ear hearing disorder with a microphone which delivers an audio signal, with an electronic signal processing and amplification unit which is located in an audio signal-processing electronic hearing aid path, with an implantable electromechanical output converter and with a unit for power supply of the implant, this object is achieved in accordance with the invention by the hearing aid for rehabilitation of tinnitus being provided with an electronic module which generates the signals necessary for tinnitus masking, or for a noiser function, and feeds them into the audio signal processing path of the hearing implant.
The hearing aid of the invention makes it possible, using a single active, at least partially implantable system, to treat not only inner ear damage, but also and at the same time, tinnitus. Stigmatization of the patient by visible external hearing aid parts is kept small in the case of a partially implantable simultaneous therapy system, and it is completed avoided in a fully implantable device. The surgery necessary for at least partial implantation of the combination device and the associated residual risks do not exceed what must be tolerated anyway in an at least partially implantable hearing aid alone or in an at least partially implantable tinnitus masker alone.
As the implantable electromechanical output converter especially a converter as per U.S. Pat. No. 5,277,694 is suitable, i.e. a converter in which one wall of the converter housing is made as a vibratory membrane which together with a piezoelectric ceramic wafer applied to the inside of the membrane represents an electromechanically active heteromorphic composite element.
Another converter design suitable for these purposes is described in the co-pending, commonly owned U.S. patent application Ser. No. 09/275,872. It is a converter arrangement for partially or fully implantable hearing aids for direct mechanical excitation of the middle ear or inner ear, which is provided with a housing which can be fixed at the implantation site with respect to the skull and with a mechanically stiff coupling element which can move relative to the housing, the housing containing an electromechanical converter with which the coupling element can be caused to vibrate; these vibrations are transmitted to the middle ear ossicle or directly to the inner ear after completed implantation of the converter arrangement. The electromechanical converter is made as an electromagnet arrangement which has a component which is fixed relative to the converter housing, especially a ring coil, and a vibratory component, preferably in the form of a permanent magnetic pin which dips into the center opening of the ring coil and which is connected to the coupling element such that the vibrations of the vibratory component are transmitted to the coupling element.
However, a converter of the type described in the co-pending, commonly owned U.S. patent application Ser. No. 09/311,563 is also advantageous. It is a converter for partially or fully implantable hearing aids for direct mechanical excitation of the middle ear or inner ear which is provided with a housing which can be fixed at the implantation site and with a mechanically stiff coupling element which can move relative to the housing, the housing containing a piezoelectric element with which the coupling element can be caused to vibrate; these vibrations are transmitted to the middle ear ossicle or directly to the inner ear after completed implantation of the converter, and in the housing, there being an electromagnet arrangement which has a component which is fixed relative to the housing and has a vibratory component which is connected to the coupling element such that the vibrations of the vibratory component are transmitted to the coupling element. This converter has the advantage that the frequency response of the converter can be improved compared to both purely piezoelectric and purely electromagnetic systems, so that an adequate hearing impression at a sufficient loudness level is enabled. In particular, a largely flat frequency response of the deflection of the coupling element can be implemented in a wide frequency band at a sufficiently high stimulation level and low power consumption.
In the hearing aid according to the invention, preferably patient-specific signal parameters for tinnitus masking or the noiser function can be individually adapted to the requirements and pathological demands of the patient by means of an electronic unit.
The electronic signal processing and amplification unit can have an amplifier connected downstream of the microphone, an audiological signal processing stage supplied with the output signal of the amplifier and a driver amplifier connected upstream of the electromechanical output converter. Advantageously, the electronic module can be provided with a signal generator arrangement for generating the signals necessary for tinnitus masking or the noiser function, and a summing element connected between the signal processing stage and the driver amplifier, via which both the output signal of the audiological signal processing stage and also the output signal of the signal generator arrangement pass to the driver amplifier.
However, according to a modified embodiment of the invention, there can also be a digital signal processor as the audiological signal processing stage which is designed both for conditioning of the audio signal and also for generating the signals necessary for tinnitus masking or the noiser function and for combining the latter signals with the audio signal. In this case, an analog to digital converter can be connected upstream and a digital to analog converter downstream of the signal processor. The digital to analog converter and the driver amplifier can be combined in one module.
The signal processor is preferably equipped with a data storage for storing the patient-specific, audiological adaptation parameters and/or parameters for generating the signals for tinnitus masking or the noiser function.
To control at least one part, and preferably all of the signal processing and/or signal generating stages, there can advantageously be a microcontroller which has a data store for storing patient-specific, audiological adaptation parameters and/or the operating parameters of the signal generator arrangement.
However, the signal processor can also be designed itself for controlling at least a part and preferably all of the signal processing and/or signal generating stages.
For data input into the data store, a telemetry unit is suitable which communicates by wire or wirelessly with an external programming system.
If the hearing aid is made to be fully implantable, preferably the signal processing and amplification unit which is in the electronic hearing aid path, the electronic module for generating and feeding the signals necessary for tinnitus masking or the noiser function and the telemetry unit as the electronic module are housed together with the power supply unit in a hermetically sealed and biocompatible implant housing. Here, the electronic module is advantageously connected via an implant line to a microphone which can be implanted subcutaneously in the rear wall of the auditory canal and via an implantable line to the electromechanical output converter. This connection can be made permanent or detachable. For a detachable connection, especially a plug-in connection as is described in particular in U.S. Pat. 5,755,743 is suitable. One such connection arrangement has at least a first contact, at least one second contact supported on an elastic body and a sealing mechanism for causing the face of the first contact to engage the face of the second contact, the first contact being surrounded by at least one sealing crosspiece which is pressed into the elastic body when the contacts engage and which seals the contacts to the outside.
The output converter can be coupled, preferably via a coupling element, to an ossicle of the middle ear chain for transmission of the output-side mechanical converter vibrations. Especially the approaches of the type described in U.S. Pat. Nos. 5,277,694 and 5,941,814 are suitable for this purpose. Here, advantageously, an actively vibratory part of the output converter can be joined mechanically securely to a connecting rod which is coupled via a coupling element to part of the ossicle chain. To adjust the relative location of the connecting rod and coupling element and to fix these elements in the adjusted relative position, the coupling element is preferably made sleeve-shaped, at least in the fixing area, and it can be plastically cold-deformed by means of a crimping tool, while the connecting rod is made bar-shaped, at least in the fixing area, is provided with a rough surface, and under the influence of the crimping force applied with the crimping tool, it cannot be plastically cold-deformed, in the fixed state the sleeve-shaped part of the coupling element deformed by cold flow by the crimping force being attached permanently and without play on the bar-shaped part of the connecting rod. The end of the connecting rod which is at a distance from the output converter, however, can also be inserted into a hole of one part of the ossicle chain and fixed there.
Furthermore, the output converter can also be designed such that it can be coupled via an air gap to the ossicle chain or to the inner ear, as is described in particular in U.S. Pat. No. 5,015,225.
A fully implantable hearing aid, in another embodiment of the invention, includes an external system for transcutaneous transfer of patient-specific hearing aid and tinnitus masking or noiser programming data to the implant-side telemetry unit.
As the power supply unit, in particular a primary battery or a secondary, rechargeable element, i.e., a rechargeable battery, can be considered. In the latter case, the telemetry unit is additionally made preferably as a power receiving circuit for implant-side availability of recharging energy for the power supply unit, while the external system is, at the same time, built as a charger. In particular, a charging system of the type known from U.S. Pat. No. 5,279,292 or arrangements of the type that are described in commonly-owned, co-pending U.S. patent application Ser. Nos. 09/311,565 and 09/311566 are suitable for this purpose.
It is also possible to provide a portable remote control unit for setting or changing the hearing aid and tinnitus masking or noiser functions.
In a partially implantable system, an implant part preferably has, in addition to the output converter, a power and signal receiving interface and an electronic system connected between the receiving interface and the output converter, with the components necessary for power supply and data regeneration, and the external system part comprises the microphone, an electronic module with the signal processing unit in the hearing aid path and with the electronic module which is necessary for generation and feed of the signals necessary for tinnitus masking or the noiser function, a driver unit, and a power and signal transmitting interface connected to the output of the driver unit.
Furthermore, the partially implantable hearing aid includes, preferably, an external system for transfer of patient-specific hearing aid and tinnitus masking or noiser function programming data to the electronic module of the external system part.
In the following, advantageous embodiments of the invention are explained in conjunction with the accompanying drawings.