Electrical audio signal processing systems and devices – Monitoring/measuring of audio devices – Testing of hearing aids
Reexamination Certificate
1999-08-06
2004-09-07
Harvey, Minsun Oh (Department: 2644)
Electrical audio signal processing systems and devices
Monitoring/measuring of audio devices
Testing of hearing aids
C600S025000
Reexamination Certificate
active
06788790
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to partially and fully implantable hearing systems for rehabilitation of a pure sensorineural hearing loss or combined conduction and inner ear hearing loss with mechanical stimulation of the impaired ear.
2. Description of Related Art
Recently, partially and fully implantable hearing aids for rehabilitation of a pure inner ear hearing disorder or combined sound conduction and inner ear hearing disorder with mechanical stimulation of the damaged ear have become available on the market or will soon be available (journal HNO 46:844-852, 10-1998, H. P. Zenner et al., “Initial implantations of a completely implantable electronic hearing system in patients with an inner ear hearing disorder”; journal HNO 46:853-863, 10-1998, H. Leysieffer et al., “A completely implantable hearing system for inner ear hearing handicapped: TICA LZ 3001”; U.S. Pat. Nos. 5,277,694; 5,788,711; 5,814, 095; 5,554,096; and 5,624,376). Especially in fully 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. Basically, in these implantable systems, the output signal is a mechanical vibratory stimulus which directly excites the middle ear or inner ear. The coupling of the mechanical excitation which is produced by an electromechanical transducer takes place by direct mechanical connection of the vibrating transducer element to the ossicle chain or an ossicle of the middle ear or to the inner ear (commonly assigned U.S. patent application Ser. No. 09/042,805) or by force coupling via an air gap in, for example, electromagnetic transducers.
The coupling quality of the mechanical excitation is influenced by many parameters and contributes significantly to rehabilitation of hearing loss and to the perceived hearing quality. Intraoperatively, this quality of coupling can only be assessed with difficulty or not at all, since the amplitudes of motion of the vibrating parts even at the highest stimulation levels are in a range around or far below 1 &mgr;m , and therefore, they cannot be assessed by direct visual inspection. Even as this is done using other technical measurement methods, for example, by intraoperative laser measurements (for example, laser doppler vibrometry), the uncertainty of a long-term stable, reliable coupling remains, since this can be adversely affected among others by necrosis formation, tissue regeneration, air pressure changes and other external and internal actions. In particular, in completely implantable systems, it remains necessary to be able to assess the coupling quality of the transducer, since in a full implant, it is not possible to separately measure individual system components at their technical interfaces if, for example, the implant wearer complains of inferior transmission quality which cannot be improved by reprogramming of individual audiologic adaptation parameters, and therefore, surgical intervention to improve the situation cannot be precluded. Even if this is not the case, there is fundamental scientific interest in having available a reliable monitor function of long term development of the quality of the transducer coupling.
International Patent Application Document WO 98/36711 proposes a method for this purpose which works with objective audiometric methods such as, for example, ERA (electric response audiometry), ABR (auditory brainstem response) or electrocochleography in partially and fully implantable systems with mechanical or electrical stimulation of the impaired or failed hearing. By electrical tapping via external head electrodes or implanted electrodes, stimulus responses which are evoked by application of suitable stimulating effects are objectively determined. The advantage of this method lies in that intraoperatively objective data of transmission quality can be obtained under full anesthesia. However, the major disadvantage, among others, is that these objective audiometric methods can only be of a qualitative nature, delivering essentially only data at the auditory threshold and/or only to a limited extent above threshold, and in particular, have only inadequate quantitative accuracy in frequency specific measurements. The subjective evaluation of transmission quality and subjective audiologic measurements in the range above threshold as, for example, loudness scales are not possible.
SUMMARY OF THE INVENTION
The primary object of this invention is to devise a partially or fully implantable hearing system which makes it possible, while circumventing these defects by psychoacoustic measurements, i.e, by subjective patient responses, to determine the coupling quality of the electromechanical transducer to the middle or inner ear without other biological-technical interfaces having been incorporated into the evaluation which adversely effect the reliability of the determination of transducer coupling quality.
Proceeding from a partially and fully implantable hearing system for rehabilitation of a pure sensorineural hearing loss or combined conduction and inner ear impairment with a microphone which delivers an audio signal, an electronic signal processing and amplification unit which is located in an audio signal processing electronic hearing system path, an implantable electromechanical output transducer and a unit for power supply of the implant, this object is achieved in accordance with the invention by an electronic audiometer unit being added to the hearing system and generating the audiometry signals for an audiologic, subjective study and evaluation of the coupling quality of the electromechanical output transducer and feeding it into the audio signal processing path of the hearing implant.
The audiometer module preferably is formed of one or more electronic signal generators which can be adjusted or programmed from the outside and which feed an electrical audiometry signal into the signal processing path of the implant. The electromechanical output transducer of the implanted hearing system becomes technically reproducible by the audiometer module and is directly triggered electrically in a quantitatively determined manner; in this way, adulteration of the stimulation level is prevented, as can occur, for example, by headphone and especially acoustic free field presentation of the audiometric test sound because, here, the sensor or microphone function with all pertinent variabilities is incorporated into the psychoacoustic measurement.
The system in accordance with the invention has the advantage, among others, that, for example, frequency-specific auditory threshold measurements with pure sinusoidal tones or narrowband signals (for example, third octave noise) can be very easily reproduced at longer study time intervals. Furthermore, the acquisition of reproducible psychoacoustic data in the supraliminal area, for example, loudness scalings, is also possible. In addition, by offering pure signals such as, for example, sinusoidal signals, nonlinearities can also be subjectively interrogated which can arise, for example, by diminishing coupling quality. These studies are possible only to a limited extent or not at all by the objective measurement methods described at the beginning on the basis of evoked potentials.
Basically, in the fully implantable systems, the approach according to the invention yields the advantage that the parameters of signaling such as, for example, the electrical operating level of the electromechanical implant transducer are quantitatively exactly determined and can be reproduced by the generators within the implant and are not subject to fluctuations, as occur, for example, in a full implant by acoustic headphone presentation of the test signals. In this last case, the transmission function of the implanted acoustic sensor (microphone) is incorporated into transmission at the same time. The sensor function can also be subject to time fluctuations and
Cochlear Limited
Harvey Minsun Oh
Nixon & Peabody LLP
Pendleton Brian
Safran David S.
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