Pilot study on evaluation indices for aircraft noise considering sound quality

In Japan, Lden is currently used as an evaluation index for aircraft noise. It is based on the A-weighted sound pressure. It evaluates differences in noise loudness, but it does not necessarily take into account differences due to changes in sound quality. Over the past several decades, single event of aircraft noise has been significantly reduced. As a result, we have experienced a change from the "noisy" sound quality of the old generation jets to the "soft" sound quality of the recent aircrafts. Has the sound quality really improved, and has its improvement been evaluated? On the other hand, since the 2000's, we have sometimes experienced hearing the extraordinary tonal sounds from landing aircraft. It has the characteristics of pure tonal tone with 250-500 Hz and has a short duration and a prominent level fluctuation. Doessuch a sudden tonality change, which is also negatively perceived, not affect the evaluation? This paper describes the results of trial calculation in order to examine the possibility of evaluating aircraft noise considering its sound quality, based on several indices such as EPNL, loudness, sharpness, and Tonal Audibility (TA), in addition to the A-weighted noise (LAmax, LEA), and its comparative verification including differences in aircraft generations.