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A method of mapping a sound field using sound quality metrics has been investigated with an aim of identifying noise sources based on their sound characters rather than traditional measures such as sound pressure level (SPL) and intensity. The method having 11 metrics was implemented in four different array applications, namely near-field acoustical holography, planar beamforming, spherical beamforming, and patch acoustical holography. The sound quality metrics (SQ) mapping was applied to diesel engine measurements as well as vehicle interior measurements. In both applications, there have been a number of attempts to identify impulsive noise sources and therefore in this investigation an impulsiveness metric was developed. The proposed metric was validated against ideal impulses as a function of impulse repetition frequency, amplitude and duration of impulses.

The interior noise produced in a car while accelerating was studied from the aspect of sound quality. The quality of interior noise produced in various types of cars was first assessed subjectively by Semantic Differential method. These data were then compared with the data obtained by objective assessment. Two types of cars having two types of sound quality were then produced by making necessary modifications on the basis of the comparison. The new information gained on sound improving technology which is very effective in setting up pleasant sound environment, has been discussed in this paper.