Sound Quality Evaluation of Exhaust Note During Acceleration

This paper presents the results of an evaluation that focused on time-related changes in the sound quality of automotive exhaust noise during acceleration. The sound quality factors evaluated are a powerful feeling, a buoyant feeling and an accelerating (rising) feeling, which are the three principal factors of the perceived sound quality of sports cars. The test sounds include original and processed sounds. Three original sounds are measured samples of the exhaust noise for three types of six-cylinder-engine vehicles that are represented each above three factors. The processed sounds are obtained by modifying the order component level and the other features of the original sounds. The procedure used in the evaluation is a method of Continuous Assessment by Predefined Categories(CAPC), which facilitates an evaluation of constantly changing sound qualities. The subjective values thus obtained and various physical quantities, including time-related changes in the sound pressure level and frequencies, were subjected to a multiple regression analysis to quantify each of the three factors. The objective values derived as a combination of various physical quantities for each factor show good agreement with the corresponding subjective values.