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Effect of the excitation signal type on the absorption coefficient measurement using the impedance tube

2020; Elsevier BV; Volume: 171; Linguagem: Inglês

10.1016/j.apacoust.2020.107659

1872-910X

A.C. Corredor-Bedoya, Byron Alejandro Acuña Acurio, Alberto Luiz Serpa, Bruno Masiero,

Vehicle Noise and Vibration Control

This work evaluates the effect of the excitation signal used when measuring the absorption coefficient on an impedance tube. This paper aims to offer some guidance on the selection of the excitation signal to perform sound absorption measurements using the impedance tube. Four possible excitation signals defined in ISO 10534-2 Standard were studied: two of them, random noise and two of them sine sweep signals. Some hypotheses tests were executed to assess the homogeneity of each measurement. The signal-to-noise ratio (SNR) was also computed to verify the measurement quality. The results show that the best performing approach was accomplished using a logarithmic sweep, giving more precise sound absorption curves with an SNR of 34.15 dB. Random signals reported similar SNR (greater than 30 dB) after executing an average with 100 repetitions.