U.S. Patent No. 8,014,871, issued on September 6, 2011 to Cochlear Limited, of Macquarie University, New South Wales, Australia, discloses an interferometry-based microphone that can be part of an implanted prosthetic hearing device.
Cochlear implants are prosthetic hearing devices that have been successful in restoring hearing in individuals whose deafness is due to impairment of the inner ear (cochlea) but who still have an operable neural auditory path to the brain. Such cochlear implants utilize an array of stimulation electrodes implanted into the cochlea and controlled by a sound processor worn on the outside of the scalp. The sound processor uses inductive coupling to transmit signals indicative of detected sound through the skull to the stimulation electrodes. The electrodes then stimulate a working portion of the neural auditory path, which are interpreted as sounds by the individual’s brain. My mom has cochlear implants in both of her ears, and they have greatly improved her quality of life.
According to the ’871 patent, totally implantable prosthetic hearing systems promise to provide more improved sound quality, but there can be challenges in the use of a totally-implantable microphone, such as “optimizing the coupling of sound between the tissue and the device, size restrictions due to the space available in the target implant location such as the middle ear, and the need to deliver sufficient gain to aid severe hearing loss.” The ’871 patent discloses a system in which sound vibrations of a portion of the biocompatible housing are detected by two interferometers configured to detect two sound frequency ranges. According to the ’871 patent, ”[t]he use of an interferometer microphone results in a substantially more robust and sensitive prosthetic hearing device” which can use a relatively thick diaphragm which is less prone to damage during manufacture, handling, and implantation.
According to its website, Cochlear Limited is an Australia-based company with a “history of innovation,” based on the pioneering work of Dr. Graeme Clark. This history of innovation is borne out by the USPTO database, which lists 144 U.S. patents issued to Cochlear Limited since 1995, 36 of which have issued in 2011.