Publication Date: 2001-Jan-16
The IP.com Prior Art Database
A binaural emulator provides the ability to perceive the direction of a sound source even though only a single ear receives a signal. The binaural emulator uses directional microphones to convert sound waves to electrical signals; the magnitudes of the signals depend on the receive patterns of the directional microphones. The electrical signals are processed independently so that unique codes are superimposed upon each signal. The signals are then summed, and either provided as an input to a hearing aid or converted to the stimulation current provided to an implantable cochlear stimulator. However, the ideas presented are not limited to only two sound sources, and may be applied to a plurality of sound sources, thus providing, for example, the ability to perceive that the source of a noise is to the rear of the hearer. The signals may be encoded by frequency, coloring each signal uniquely.
Known cochlear stimulation systems provide only monaural hearing. Implanting two implantable cochlear stimulators would provide binaural hearing, but is not considered practical and is generally not covered by medical insurance. As a result, the patient is limited to monaural hearing capability only.
Accordingly, there is a need for a cochlear stimulation system capable of providing binaural hearing through a single implantable cochlear stimulator. The ideas presented herein satisfy such need.
Described is a binaural emulator for cochlear stimulation systems. The binaural emulator utilizes signals from two or more separate directional microphones, preferably located on the patient's head. The electrical signals from each microphone are uniquely encoded and summed. The resulting signal is used to stimulate either the right or the left cochlea. The patient's higher level neural processes learn to distinguish the origins of the signals, and thereby provide sound direction information to the patient. In one arrangement, microphones positioned on the right and left sides of the patient's head provide the patient with the ability to distinguish a sound coming from the patient's right versus the patient's left based on the magnitude of the encoded signals.
An additional feature provides an ability to distinguish sound originating from behind the patient, by pointing one or more directional microphones directed to the rear of the patient (or the patient's head). The ability to resolve sounds from behind advantageously enables the patient to participate in employment related activities, or recreational activities, that might otherwise prove hazardous.
A method is provided for binaural hearing, to hearing aid users, through a single ear. A second microphone is located on the side of the patient's head opposite the first microphone in the hearing aid. The signals from the microphones are encoded and summed. The resulting signal is provided to the patient through one ear. Similarly, a patient who has lost the hearing ability of one ear may re-gain binaural hearing.
A further feature provides a method of encoding multiple signals for summation to use for stimulation of a single cochlea. The signals are independently filtered by filters with distinct frequency responses; this results in different coloring of the sound from reach microphone. The patient's higher level neural processes are then able to distinguish the independent sources of the signals.
Shown in FIG. 1 is a binaural emulating cochlear stimulation system that includes a signal processor, as it might appear on a patient's head, comprising a first microphone 10A, a second microphone 10B, and an external device 12. An implantable part comprising an internal device 16 and an electrode array 20 is implanted and therefore not visible in FIG. 1. Typically, the first microphone 10A will be integrated into the external device 12, but this is not a functional requireme...