Patent ID: 7496206

Claim:
A hearing aid comprising: hearing aid circuitry operable according to a first hearing aid function and according to a second hearing aid function; a switching signal generator connected to said hearing aid circuitry that generates a switching signal that causes said hearing aid circuitry to switch between respective operation according to first and second hearing aid functions; a signal source; and a Wheatstone bridge circuit connected between said signal source and said switching signal generator, said Wheatstone bridge comprising a first branch containing a single magnetic field-controlled ferrite component that exhibits a magnetic field-dependent impedance change dependent on a magnetic field, a second branch containing a first ohmic resistor, a third branch containing a second ohmic resistor, and a fourth branch containing a capacitive element, said impedance change of said ferrite component, when said magnetic field is present, changing an output status of said Wheatstone bridge that causes said switching signal generator to switch said hearing aid circuitry.