Small Car Interior Noise Sound Quality Evaluation

Nowadays noise pollution has become a more and more serious environmental problem, and cars and mechanical and electronical products are main noise sources in daily life. The research work in this thesis is focused on the estimation of sound quality for cars and air-conditions. Through a great number of objective analysis for sound characteristics and subjective audition experiments, new sound quality parameters used in mechanical and electronical products are proposed.Firstly, the source characteristics of cars and air-conditions are analyzed. Then A-weighted sound level, sharpness, fluctuation and loudness are chosen to be the fundamental parameters for objective sound quality evaluation of mechanical and electronical products. Because loudness is most fundamental of the four parameters, masking characteristics of human ears are applied in the sound estimation and based on Zwickcr theory and ERB method, a simple and accurate approach is proposed to calculate loudness.Secondly, rank marking and paired comparison approaches are used to subjective sound quality. On the base of annoyance and its practicability, the classified system of estimating the sound quality of cars is give. Then the parameter of the sound quality (PSQ) using for cars is presented. Subjective audition experiments for evaluating the sound quality is designed and accomplished, and a large number of experimental datum are obtained. Classified system of estimating the sound quality and PSQ model are proved right.Finally, results of the subjective evaluation for sound samples are gained and based on processing the datum of the subjective experiment, formulae for PSQ of cars are given. In addition, sound quality evaluation using neural network and fuzzy evaluation are also discussed.