Perceptual representation of aircraft sounds

This study is part of a research program supported by the European Commission through the Sixth framework program: “Sound Engineering For Aircraft”. This program is devoted to the acoustic features of aircraft noise which could be improved by aircraft manufacturers from a sound design point of view. The present study focuses on aircraft sound perception. Fourteen different aircraft sounds are studied and correspond to seven take offs and seven landings. Preference tests are carried out in order to assess the sound agreement using a seven-point scale, each stimulus being compared to a reference sound. For each pair, subjects have to justify their answer in their own words. Their descriptions are analysed in a linguistic way. Dissimilarity tests are also carried out using the same stimuli. Four perceptual factors, which explain the distance between aircrafts sounds, are extracted thanks to INDividual multidimensional SCALing (INDSCAL) analysis. They correspond to the temporal evolution of the sound level (one factor for the slope of the increase and another factor for the regularity of the increase) and to the timbre aspect (one factor for tonality and one factor for the texture of noise). The verbalisation helps to understand and interpret these dimensions. Objective classical criteria are tested to characterize these perceptual effects using correlations between objective and subjective measurements.