Method for filtering measurement signals during non-destructive material testing for surface defects or wall thickness deviations during the production of metal pipes, which method comprises the following steps: - exciting non-destructive material testing signals in a wall of the pipe, - receiving measurement signals that have been reflected off an inner surface of the pipe and, using a signal processor, - filtering the measurement signals, as a continuous, digital data stream, by means of wavelet filtering via a wavelet filter, wherein the wavelet filter consists of a cascade-like arrangement of digital decomposition filters with finite impulse response in decomposition levels, which filters operate in a point-by-point mode, wherein the measurement signals are first converted into the wavelet domain by means of wavelet transformation, in which wavelet domain the signals consist of wavelet coefficients in each decomposition level, and wherein the wavelet transformation of the measurement signals is carried out using a stationary wavelet transformation, - calculating a statistical parameter at each decomposition level from an adjustable number of already calculated wavelet coefficients of this decomposition level, - determining a threshold value at each decomposition level by multiplying the statistical parameter by an adjustable value common to all levels, - changing the wavelet coefficients at each decomposition level by hard-thresholding or soft-thresholding with regard to the threshold value of the particular decomposition level, - feeding the modified wavelet coefficients to an inverse wavelet transformation in order to obtain filtered measurement signals, wherein the inverse wavelet transformation of the modified wavelet coefficients takes place by means of a cascade-like arrangement of digital synthesis filters with finite impulse response in synthesis stages which correspond to the successive, cascade-like decomposition stages of the decomposition filters, wherein the modified wavelet coefficients of the last decomposition level are fed to a pair of inverse high-pass and low-pass filters, the values of both filters are added and divided by 2, as a result of which a mean is formed and the mean is fed to a further, subsequently higher stage, wherein delay elements of different lengths are arranged between the decomposition and synthesis FIR filters, and wherein the digital synthesis filters operate in point-by-point mode, wherein the inverse wavelet transformation of the modified wavelet coefficients is carried out using the stationary wavelet transformation, the method further comprises the steps of: - stopping the filtering of measurement signals during a measurement pause by feeding at least one additional signal, - providing the data of the previous measurement as history when the measurement is resumed. - exciting non-destructive material testing signals in a wall of the pipe, - receiving measurement signals that have been reflected off an inner surface of the pipe and, using a signal processor, - filtering the measurement signals, as a continuous, digital data stream, by means of wavelet filtering via a wavelet filter, wherein the wavelet filter consists of a cascade-like arrangement of digital decomposition filters with finite impulse response in decomposition levels, which filters operate in a point-by-point mode, wherein the measurement signals are first converted into the wavelet domain by means of wavelet transformation, in which wavelet domain the signals consist of wavelet coefficients in each decomposition level, and wherein the wavelet transformation of the measurement signals is carried out using a stationary wavelet transformation, - calculating a statistical parameter at each decomposition level from an adjustable number of already calculated wavelet coefficients of this decomposition level, - determining a threshold value at each decomposition level by multiplying the statistical parameter by an adjustable value common to all levels, - changing the wavelet coefficients at each decomposition level by hard-thresholding or soft-thresholding with regard to the threshold value of the particular decomposition level, - feeding the modified wavelet coefficients to an inverse wavelet transformation in order to obtain filtered measurement signals, wherein the inverse wavelet transformation of the modified wavelet coefficients takes place by means of a cascade-like arrangement of digital synthesis filters with finite impulse response in synthesis stages which correspond to the successive, cascade-like decomposition stages of the decomposition filters, wherein the modified wavelet coefficients of the last decomposition level are fed to a pair of inverse high-pass and low-pass filters, the values of both filters are added and divided by 2, as a result of which a mean is formed and the mean is fed to a further, subsequently higher stage, wherein delay elements of different lengths are arranged between the decomposition and synthesis FIR filters, and wherein the digital synthesis filters operate in point-by-point mode, wherein the inverse wavelet transformation of the modified wavelet coefficients is carried out using the stationary wavelet transformation, - stopping the filtering of measurement signals during a measurement pause by feeding at least one additional signal, - providing the data of the previous measurement as history when the measurement is resumed.