Psychoacoustic measurement of roughness of vehicle interior noise

Abstract

In analyzing vehicle interior noise there exists hardly any correlation between the subjective impressions of test persons and available roughness parameters. It has become necessary to develop a new roughness model for these sounds and to set up a subjective database as a basis for the analytical description of interior noise quality. This paper focuses on psychoacoustical experiments for the assessment of roughness by using different methods and different kinds of vehicle interior sounds. The analysis of the results shows that small experimental manipulations lead to a large variety of different results. The different meanings of the word roughness have to be taken into account. Each person has his or her own interpretation of roughness differing between the phenomena of roughness, r-roughness, rumble, fluctuation strength, etc. Another important point is the reduction of accidental influences of psychoacoustical parameters, like, for example, the influence of loudness on the perception of roughness. By using a special headphone–subwoofer playback system in the laboratory, it is possible to achieve ratings comparable with field experiments. As reported in a companion paper, a new generalized psycho- acoustical model of modulation parameters was successfully tested with the obtained roughness rankings.