Oticon A/s

Michael Ekelid

Jakob Nielsen

Finn Danielsen

Peter Lundh

The invention relates to a method for canceling feedback in an acoustic system comprising a microphone, a signal path, a speaker and means for detecting presence of feedback between the speaker and the microphone, the method comprising providing a LMS algorithm for processing the signal; where the LMS algorithm operates with a predetermined adaptation speed when feedback is not present; where the LMS algorithm operates an adaptation speed faster than the predetermined adaptation speed when feedback is present, and where the means for detecting the presence of feedback is used to control the adaptation speed selection of the LMS algorithm. The invention further relates to a method comprising using a highpass filter to prevent low-frequency signals from entering the LMS algorithm. The invention still further relates to a method comprising using bandwidth detection means for determining the presence of a feedback signal. The invention also relates to hearing aids for implementing these methods.

Feedback cancellation with low frequency input

The invention relates to a method for reducing feedback caused by electromagnetic interference between an induction coil and an output transducer, a voltage supply or an amplifier or a combination thereof, the method comprising: producing by means of a filter an equivalent of an electromagnetic feedback path in a system with a pickup coil and subtraction of the equivalent of the feedback signal from the input signal in order to obtain feedback reduction. The invention further relates to a device for implementing the method, the device comprising an induction coil and an output transducer, voltage supply or an amplifier or a combination thereof. The device further comprises filter means for generating an equivalent of an electromagnetic feedgack signal occurring between the induction coil and an output transducer, a voltage supply or an amplifier or a combination thereof and means for subtracting the equivalent from an input signal in order to obtain feedback reduction.

Electromagnetic feedback reduction in communication device

A method for canceling feedback in an acoustic system including a microphone, a signal path, a speaker and means for detecting presence of feedback between the speaker and the microphone, the method including providing an LMS algorithm for processing the signal; where the LMS algorithm operates with a predetermined adaptation speed when feedback is not present; where the LMS algorithm operates an adaptation speed faster than the predetermined adaptation speed when feedback is present, and where the means for detecting the presence of feedback is used to control the adaptation speed selection o the LMS algorithm, where the feedback detection means comprises bandwidth detection means for determining the presence of a feedback signal.

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Hellerup, Denmark

Michael Ekelid