An adaptive filter unit, in particular for being used as an echo canceller, comprising a first filter input, configured to receive a first electric audio signal, indicative of a first audio signal A(t); a second filter input, configured to receive a second electric audio signal, indicative of a second audio signal B(t); a memory unit arranged to provide a data exchange with a processor of the adaptive filter and comprises a delay line structure comprising at least one delay line, which contains at least an audio estimation data X(f n, A(t' 1,..., t' M(fn))) for points in time t' 1,..., t' M(fn) being before a time t 1 of a data point of the most recent audio signal received by said adaptive filter unit; the processor, arranged and configured to - receive the first and second electric audio signal (115, 125); - calculate, by a first FFT unit, and provide audio estimation data X(f n, A(t 1,..., t M(fn))) in a frequency domain by calculating a Fast Fourier Transform, FFT, of the first audio signal A(t), for frequencies f n =f 1,..., f N, wherein N is a number of FFT bins, and with a number of sampling points M(f n) of the first audio signal A(t); - calculate, by a second FFT unit, a transformed second audio signal Y(f n, B(t)), formed by a transformation of the second audio signal B(t) into the frequency domain; - receive a delayed audio estimation data provided by the memory unit, wherein the delayed audio estimation data is formed by the audio estimation data that is stored in the memory unit and comprises a frequency dependent time delay compared to the transformed second audio signal; - calculate, by a subtraction unit, a filtered audio signal by subtracting the delayed audio estimation data from the transformed second audio signal; - calculate, by a reverse FFT unit, a processed audio output signal by transforming the filtered audio signal into a time domain; and wherein the adaptive filter unit comprising a filter output, configured to provide the processed audio output signal. a first filter input, configured to receive a first electric audio signal, indicative of a first audio signal A(t); a second filter input, configured to receive a second electric audio signal, indicative of a second audio signal B(t); a memory unit arranged to provide a data exchange with a processor of the adaptive filter and comprises a delay line structure comprising at least one delay line, which contains at least an audio estimation data X(f n, A(t' 1,..., t' M(fn))) for points in time t' 1,..., t' M(fn) being before a time t 1 of a data point of the most recent audio signal received by said adaptive filter unit; the processor, arranged and configured to - receive the first and second electric audio signal (115, 125); - calculate, by a first FFT unit, and provide audio estimation data X(f n, A(t 1,..., t M(fn))) in a frequency domain by calculating a Fast Fourier Transform, FFT, of the first audio signal A(t), for frequencies f n =f 1,..., f N, wherein N is a number of FFT bins, and with a number of sampling points M(f n) of the first audio signal A(t); - calculate, by a second FFT unit, a transformed second audio signal Y(f n, B(t)), formed by a transformation of the second audio signal B(t) into the frequency domain; - receive a delayed audio estimation data provided by the memory unit, wherein the delayed audio estimation data is formed by the audio estimation data that is stored in the memory unit and comprises a frequency dependent time delay compared to the transformed second audio signal; - calculate, by a subtraction unit, a filtered audio signal by subtracting the delayed audio estimation data from the transformed second audio signal; - calculate, by a reverse FFT unit, a processed audio output signal by transforming the filtered audio signal into a time domain; and wherein the adaptive filter unit comprising a filter output, configured to provide the processed audio output signal. - receive the first and second electric audio signal (115, 125); - calculate, by a first FFT unit, and provide audio estimation data X(f n, A(t 1,..., t M(fn))) in a frequency domain by calculating a Fast Fourier Transform, FFT, of the first audio signal A(t), for frequencies f n =f 1,..., f N, wherein N is a number of FFT bins, and with a number of sampling points M(f n) of the first audio signal A(t); - calculate, by a second FFT unit, a transformed second audio signal Y(f n, B(t)), formed by a transformation of the second audio signal B(t) into the frequency domain; - receive a delayed audio estimation data provided by the memory unit, wherein the delayed audio estimation data is formed by the audio estimation data that is stored in the memory unit and comprises a frequency dependent time delay compared to the transformed second audio signal; - calculate, by a subtraction unit, a filtered audio signal by subtracting the delayed audio estimation data from the transformed second audio signal; - calculate, by a reverse FFT unit, a processed audio output signal by transforming the filtered audio signal into a time domain; and