The research of sound absorption coefficient in automobile cabs based on time delay

The material's absorption capacity can be accurately determined using a key parameter known as the absorption coefficient. However, existing techniques for measuring the absorption coefficient, such as the impedance tube and reverberation methods, have been found to have certain drawbacks, as this study has identified. In this context, the study of the phase of the sound pressure, which is determined by a pair of microphones placed at the same distances, is presented. There is a lag in obtaining the absorption coefficient at the leading edge of the absorption material. In the end, a detailed examination is carried out on a particular absorbing material, with the sound absorption coefficient derived from this technique aligning closely with the outcomes of the impedance tube approach and reverberation room technique, particularly at low frequencies of sound. In reference to a case study on the distribution of radiated energy noise from automotive engines, the measurement of absorption coefficients based on time delay is faster, as evidenced by the aforementioned method, which empirically demonstrates the effectiveness and feasibility of the proposed theory.