A maximum stable gain measurement system for a hearing assistance device, the hearing assistance device having an impulse response defining the acoustic response of a feedback path between an output of the hearing assistance device and an input of a signal processing channel of the hearing assistance device, and having an acoustic feedback canceller to cancel feedback between the output and the input, the system comprising: a white noise generator arranged to produce a white noise signal; a fixed filter programmed to receive the white noise signal as an input, and having time domain coefficients representing the impulse response; the acoustic feedback canceller comprising a first adaptive filter connected to receive the white noise signal as an input and an error signal obtained by subtracting the output of the fixed filter from the output of the first adaptive filter thereby forming a closed loop negative feedback, the first adaptive filter being programmed to adapt frequency domain coefficients using said closed loop negative feedback to reach a stable solution approximating a transfer function of the acoustic feedback path during an injection of the white noise signal by the white noise generator and to freeze said frequency domain coefficients; and a second adaptive filter connected to receive the white noise signal as an input and a second error signal obtained by subtracting the output of the acoustic feedback canceller, once the frequency domain coefficients have been frozen, from the output of the second adaptive filter, thereby forming a second closed loop negative feedback, the second adaptive filter being programmed to adapt time domain coefficients using the second closed loop negative feedback to reach a stable solution during a second injection of the white noise signal by the white noise generator; wherein the system is configured to calculate the maximum stable gain of the hearing assistance device as a function of frequency by performing a fast Fourier transform of the time domain coefficients of the second adaptive filter. a white noise generator arranged to produce a white noise signal; a fixed filter programmed to receive the white noise signal as an input, and having time domain coefficients representing the impulse response; the acoustic feedback canceller comprising a first adaptive filter connected to receive the white noise signal as an input and an error signal obtained by subtracting the output of the fixed filter from the output of the first adaptive filter thereby forming a closed loop negative feedback, the first adaptive filter being programmed to adapt frequency domain coefficients using said closed loop negative feedback to reach a stable solution approximating a transfer function of the acoustic feedback path during an injection of the white noise signal by the white noise generator and to freeze said frequency domain coefficients; and a second adaptive filter connected to receive the white noise signal as an input and a second error signal obtained by subtracting the output of the acoustic feedback canceller, once the frequency domain coefficients have been frozen, from the output of the second adaptive filter, thereby forming a second closed loop negative feedback, the second adaptive filter being programmed to adapt time domain coefficients using the second closed loop negative feedback to reach a stable solution during a second injection of the white noise signal by the white noise generator; wherein the system is configured to calculate the maximum stable gain of the hearing assistance device as a function of frequency by performing a fast Fourier transform of the time domain coefficients of the second adaptive filter.