Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2001-05-11
2003-10-21
Jastrzab, Jeffrey R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C623S010000
Reexamination Certificate
active
06636768
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an implantable microphone system useable with cochlear implants or implantable hearing aids, and more particularly to an implantable microphone system that uses a highly sensitive motion/position sensor that may be coupled to middle ear structure.
A cochlear implant is an electronic device designed to provide useful hearing and improved communication ability to individuals who are profoundly hearing impaired and unable to achieve speech understanding with hearing aids. Hearing aids (and other types of assistive listening devices) make sounds louder and deliver the amplified sounds to the ear. For individuals with a profound hearing loss, even the most powerful hearing aids may provide little to no benefit.
A profoundly deaf ear is typically one in which the sensory receptors of the inner ear, called hair cells, are damaged or diminished. Making sounds louder or increasing the level of amplification, e.g., through the use of a hearing aid, does not enable such an ear to process sound. In contrast, cochlear implants bypass damaged hair cells and directly stimulate the hearing nerves with electrical current, allowing individuals who are profoundly or totally deaf to receive sound.
In order to better understand how a cochlear implant works, and how the present invention is able to function, it is helpful to have a basic understanding of how the ear normally processes sound. The ear is a remarkable mechanism that consists of three main parts: the outer ear, the middle ear and the inner ear. The outer ear comprises the visible outer portion of the ear and the ear canal. The middle ear includes the eardrum and three tiny bones. The inner ear comprises the fluid-filled snail-shaped cochlea, which contains thousands of tiny hair cells.
When the ear is functioning normally, sound waves travel through the air to the outer ear, which collects the sound and directs it through the ear canal to the middle ear. The sound waves strike the eardrum (tympanic membrane) and cause it to vibrate. This vibration creates a chain reaction in the three tiny bones in the middle ear. These three tiny bones are medically termed the malleus, incus and stapes, but are also commonly referred to as the “hammer”, “anvil” and “stirrup”. Motion of these bones, in turn, generates movement of the oval window, which in turn causes movement of the fluid contained in the cochlea.
As indicated above, the cochlea is lined with thousands of tiny sensory receptors commonly referred to as hair cells. As the fluid in the cochlea begins to move, the hair cells convert these mechanical vibrations into electrical impulses and send these signals to the hearing nerves. The electrical energy generated in the hearing nerves is sent to the brain and interpreted as “sound”.
In individuals with a profound hearing loss, the hair cells are damaged or depleted. In these cases, electrical impulses cannot be generated normally. Without these electrical impulses, the hearing nerves cannot carry messages to the brain, and even the loudest of sounds may not be heard.
Although the hair cells in the cochlea may be damaged, there are usually some surviving hearing nerve fibers. A cochlear implant works by bypassing the damaged hair cells and stimulating the surviving hearing nerve fibers, or ganglion cells, with an electrical signal. The stimulated nerve fibers then carry the electrical signals to the brain, where they are interpreted as sound.
Representative cochlear implant devices are described in U.S. Pat. Nos. 4,267,410; 4,428,377; 4,532,930; and 5,603,726, incorporated herein by reference.
Cochlear implants currently use external microphones placed on the body that pick up sound (sense acoustic pressure waves and convert them to electrical signals) and then transmit the electrical signals to a signal processor for amplification, processing and conversion into an electrical stimulation signal (either current or voltage) that is applied to the surviving acoustic nerves located in the cochlea. Such a microphone is, by design, very sensitive, and in order to be sensitive, is by its nature very fragile. Disadvantageously, the external microphone can be damaged if it becomes wet, is dropped or is exposed to extreme conditions frequently encountered in the external environments. These fragile and sensitive microphones also restrict the user's lifestyle and activities. For example, when a user must wear a microphone, he or she is typically restricted from participation in swimming and other sports, e.g., contact sports, unless the microphone is removed during such activities. If the microphone is removed, however, the user no longer is able to hear. Moreover, many users also find external microphone cosmetically objectionable since they appear out of place and mark the user as “needing assistance”.
Middle ear microphones are known in the art. Disadvantageously, however, such prior art middle ear microphones typically require that sensors be attached between moving middle ear structures and stationary parts of the middle ear. This attachment may constrain motion and reduce or modify the performance of these moveable middle ear structures, resulting in an undesirable frequency response and/or distortion in sounds that are perceived. Further, adding too much mass to the ossicle chain or other moving structures of the middle ear may also change the dynamic behavior of the middle ear. What is needed, therefore, relative to a middle ear microphone, or a microphone coupled to middle ear structure, is a microphone that preserves the structure and dynamic performance of the middle ear as much as possible.
An example of an implantable microphone is found in U.S. Pat. No. 5,814,095, incorporated herein by reference. One technique for mounting such a microphone near the ear canal is shown in U.S. Pat. No. 5,999,632. When mounted as disclosed in the 5,999,632 patent, the implantable microphone disclosed in the U.S. Pat. No. 5,814,095 patent is not implanted in the middle ear, but is acoustically coupled to the outer ear.
From the above, it is thus evident that improvements are needed in the way users of a cochlear implant, or other hearing aid systems, sense or hear sounds, and more particularly, it is evident that improvements are needed in the microphones used with such systems, including implantable microphones coupled to middle ear structure.
SUMMARY OF THE INVENTION
The present invention addresses the above and other needs by replacing the external microphone commonly used with cochlear implants or other hearing aid systems with an implantable microphone system. Advantageously, such implantable microphone system detects “sound” by sensing the motion of middle ear components, e.g., by sensing the motion of the ossicles, without seriously degrading the performance of the middle ear components.
In one embodiment, a linear-variable-differential transformer (LVDT) is used within the middle ear to sense very small motion and position. A movable magnetic core of the LVDT is attached to the ossicies or other moving structure within the middle ear in order to measure their relative motion. Advantageously, the movable core need not be attached to any other structure. As the core of the LVDT is displaced from side-to-side by motion of the ossicles (or other movable members within the middle ear), which motion is created by audio signals (sound waves) that impinge upon the tympanic membrane, a modulated signal is induced in the windings of the transformer. This modulated signal has a phase change associated therewith that can readily be detected using conventional detection means. Such detected phase change may then be readily converted into a representation of the audio signal impinging upon the tympanic membrane.
In another embodiment, the movable plate of a movable-plate differential capacitor (MPDC) is attached to the ossicles or other movable structure of the middle ear in order to measure the relative motion thereof. Advantageously, the movable plate of the MPDC need not be attached to any othe
Advanced Bionics Corporation
Gold Bryant R.
Jastrzab Jeffrey R.
Oropeza Frances P.
LandOfFree
Implantable mircophone system for use with cochlear implant... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Implantable mircophone system for use with cochlear implant..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Implantable mircophone system for use with cochlear implant... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3126556