A method of estimating acoustic feedback in a hearing instrument in order to reduce the impact of tonal components of acoustic feedback. The hearing instrument comprises an input transducer, an output transducer, a forward path being defined between the input transducer and the output transducer, a signal processing unit defining an input side and an output side of the forward path, and a feedback loop from the output side to the input side. The feedback loop comprises a feedback path estimation unit receiving first and second estimation input signals from the input and output side of the forward path, respectively, wherein the first and second estimation input signal paths comprise first and second long term prediction filters P(z), the feedback cancellation system being adapted to provide that the variable parameters of at least one of the long term prediction filters are estimated based on the filter input signal.