Comparison of noise characteristics in airplanes and high-speed trains
Yoshiharu Soeta, Ryota Shimokura

This study investigated the characteristics of noise in trains and airplanes to determine its effect on passengers. The noise was recorded using a dummy head or binaural microphones. The data were analyzed using an autocorrelation function (ACF) and an interaural cross-correlation function (IACF). From the ACF analysis, the following were analyzed: (1) the energy represented at zero delay, Φ(0), which corresponds to the equivalent continuous A-weighted sound pressure levels, LAeq, (2) the time delay of the first maximum peak, τ1, (3) its amplitude, φ1, which corresponds to the
pitch and pitch strength, and (4) width of the first decay, WΦ(0), which corresponds to the spectral centroid. From the IACF analysis, the interaural cross-correlation coefficient (IACC), which corresponds to subjective diffuseness, and the width of the peak, WIACC, which corresponds to apparent source width, was analyzed. The median values of LAeq were approximately 73?77 dB in airplanes and 64?72 dB in high-speed trains. The values of τ1 in high-speed trains were centered approximately 2, 3, and 4 ms The values of τ1 in airplanes were centered approximately 4 and 6 ms. The values of IACC in high-speed trains . was very high.

Key words: Autocorrelation function (ACF), Interaural cross-correlation function (IACF), Sound quality