Comparison of Noise Compensation Methods for Room Acoustic Impulse Response Evaluations

Noise that is part of the measured impulse responses is inevitable but can have a large impact on the evaluation of room acoustic parameters. Five well-known and widely used noise compensation methods are discussed and their performances are compared in this study. Two evaluation approaches are used to test the different methods: A simple parametric model to simulate the envelope of an impulse response including measurement noise, and in a second approach, special designed long-term measurements. These were conducted to be able to evaluate the errors as a function of the noise level. The results that are obtained using the model and the measurement approach are consistent with each other. When these methods are used to suppress noise effects, their performances differ significantly. This is also true for the three methods that are compliant with ISO 3382. Four methods cause systematic errors depending on the peak-signal to noise ratio. The reverberation time is more sensitive to noise than energy parameters such as clarity or definition. A comparison of the different excitation signals that are used for the measurement approach shows that there is no difference with regard to sine sweeps and maximum length sequences, if no impulsive noise or nonlinearities occur.