Application of High-Density Sound Absorbing Materials for Improving Low-Frequency Spectral Flatness in Room Response

A room impulse response obtained for complex-valued boundary conditions on wall surfaces was used to determine the frequency response of arbitrary shaped room. Based on theoretical findings, a numerical procedure was developed to test the effectiveness of a high-density sound absorbing material in improving low-frequency spectral flatness. The impedance of absorbing material was determined using the two-parameter Komatsu model. The simulation results have shown that the smoothing effect of the frequency response becomes apparent when the thickness of absorbing material is large enough. This is because as the material thickness increases, the sound absorption tends to increase at lower frequencies.