Patent ID: 7844063

Claim:
A hearing aid apparatus designed for compensating acoustic feedback from an earpiece to a microphone and electromagnetic feedback from the earpiece to an electromagnetic receiver or a following electrical component, the apparatus comprising: a microphone adapted for use as a first input signal transducer; an electromagnetic receiver adapted for use as a second input signal transducer; an earpiece adapted for use as an output signal transducer from which an acoustic output signal is fed back to the microphone via an acoustic feedback path and an electromagnetic output signal is fed back to the electromagnetic receiver via an electromagnetic feedback path; a signal processing device connected between the first and second input signal transducers and the output signal transducer; a first weighting unit configured to adjust a signal from the microphone in accord with a first selectable weighting factor, the first weighting unit positioned between the microphone and the signal processing device; a second weighting unit configured to adjust a signal from the electromagnetic receiver in accord with a second selectable weighting factor, the second weighting unit positioned between the electromagnetic receiver and the signal processing device; a first adder positioned to add the signal from the microphone to the signal from the electromagnetic receiver after each signal has been adjusted in accord with a selected weighting factor; a first timing element positioned between one of the input signal transducers and the first adder to adjust one of the signals received by the adder relative to an acoustic feedback delay characteristic; a second adder positioned between the first adder and the signal processing device to adjust an output from the first adder with a compensation signal; and a single adaptive filter connected to the second adder to generate, as the compensation signal, a signal for simultaneously compensating the acoustic feedback and the electromagnetic feedback; and a second timing element positioned between the earpiece and the single adaptive filter to introduce a delay to the compensation signal, which delay corresponds to a propagation time of the acoustic feedback signal, wherein the first timing element adjusts one of the signals received by the adder by introducing a delay which corresponds to a propagation time difference between the acoustic and electromagnetic feedback signals.