A system for estimating the power spectral density of acoustical background noise; the system comprises: a sensor unit for obtaining a noise signal (MIC(ω)) representative of the background noise; a power spectral density calculation unit that is adapted for continuously determining the current power spectral density from the noise signal and is adapted for providing a corresponding power spectral density output signal (PsdMic(ω)); a time domain signal smoothing unit that is adapted for smoothing the power spectral density output signal PsdMic(ω)) in the time domain and is adapted for providing a resulting timely smoothed signal; a frequency domain signal smoothing unit that is adapted for smoothing the timely smoothed signal received from the time domain signal smoothing unit in the frequency domain and is adapted for providing a resulting smoothed power spectral density signal (SmoothedPsdMic(ω)); an increment calculation unit that is adapted for calculation of an increment (Inc((ω)) depending on an estimate value of the power spectral density of the background noise (PsdNoise(ω)); a decrement calculation unit that is adapted for calculation of a decrement (Dec(ω)) depending on the estimate value of the power spectral density of the background noise; and an estimate signal smoothing unit that is adapted for calculation of the estimate value of the power spectral density of the background noise (PsdNoise(ω)) from the increment (Inc((ω)) and decrement (Dec(ω)); where, if the value of the smoothed power spectral density (SmoothedPsdMic(ω)) currently determined in a new calculation cycle is larger than the estimate value of the power spectral density of the background noise (PsdNoise(ω)) determined in the previous calculation cycle, the increment value (Inc(ω)) is increased, starting from a minimum increment value (Inc(ω)), by a predetermined amount (ΔInc) until a maximum increment value (IncMax) is reached; and if the value of the smoothed power spectral density (SmoothedPsdMic(ω)) currently determined in a new calculation cycle is smaller than the estimate value of the power spectral density of the background noise (PsdNoise(ω)) determined in the previous calculation cycle, the decrement value (Dec((ω)) is increased, starting from a minimum decrement value (DecMin), by a predetermined amount (ΔDec) until a maximum decrement value (DecMax) is reached. a sensor unit for obtaining a noise signal (MIC(ω)) representative of the background noise; a power spectral density calculation unit that is adapted for continuously determining the current power spectral density from the noise signal and is adapted for providing a corresponding power spectral density output signal (PsdMic(ω)); a time domain signal smoothing unit that is adapted for smoothing the power spectral density output signal PsdMic(ω)) in the time domain and is adapted for providing a resulting timely smoothed signal; a frequency domain signal smoothing unit that is adapted for smoothing the timely smoothed signal received from the time domain signal smoothing unit in the frequency domain and is adapted for providing a resulting smoothed power spectral density signal (SmoothedPsdMic(ω)); an increment calculation unit that is adapted for calculation of an increment (Inc((ω)) depending on an estimate value of the power spectral density of the background noise (PsdNoise(ω)); a decrement calculation unit that is adapted for calculation of a decrement (Dec(ω)) depending on the estimate value of the power spectral density of the background noise; and an estimate signal smoothing unit that is adapted for calculation of the estimate value of the power spectral density of the background noise (PsdNoise(ω)) from the increment (Inc((ω)) and decrement (Dec(ω)); where, if the value of the smoothed power spectral density (SmoothedPsdMic(ω)) currently determined in a new calculation cycle is larger than the estimate value of the power spectral density of the background noise (PsdNoise(ω)) determined in the previous calculation cycle, the increment value (Inc(ω)) is increased, starting from a minimum increment value (Inc(ω)), by a predetermined amount (ΔInc) until a maximum increment value (IncMax) is reached; and if the value of the smoothed power spectral density (SmoothedPsdMic(ω)) currently determined in a new calculation cycle is smaller than the estimate value of the power spectral density of the background noise (PsdNoise(ω)) determined in the previous calculation cycle, the decrement value (Dec((ω)) is increased, starting from a minimum decrement value (DecMin), by a predetermined amount (ΔDec) until a maximum decrement value (DecMax) is reached.