Acoustics Acoustic Characteristic of Car Horn Sound

This paper presents an objective evaluation method for the perceived quality of a car horn sound based on a psychoacoustic metric and subjective test. A new psychoacoustic metric called the "spectrum decay" (SD) is developed to evaluate a luxury timbre in the sound quality of the horn. The SD slope is found from spectrum analysis of the interior sounds produced by car horns. The interior sounds are measured and recorded from ten sampled passenger cars. The measured horn sounds are also evaluated subjectively by 41 subjects to extract the "luxury" factor. To validate the SD slope, eight synthetic sounds with a variety of SD slopes are designed. The synthetic sounds are also subjectively evaluated by the same 41 subjects. Two sound quality indexes for car horn sound are developed based on the correlation between the SD slope and subjective ratings of the synthetic sounds. One index uses a linear relationship between the SD slope and subjective rating but has a limit to its utility (i.e., the SD slope should be less than 10). The sound quality indexes are applied to the estimation of sound quality of horn sounds of ten passenger cars measured inside the cars. Correlations between the estimated subjective rating and subjective ratings evaluated by the subjects are sufficient (linear index: R = 0.84 p < 0.004, nonlinear index: R = 0.91, p < 0.001) for validation of the sound quality index.