Study On The Construction Machinery Sound Quality Evaluation System

With the rapid footstep of our country’s modern construction, engineering machinery products play a very important role as the main tools. Then, the noise reduction of engineering machinery products becomes the urgent the problem. A weighting sound pressure level is the traditional way of noise assessment in the engineering machinery products, but there are some limitations in the evaluation of noise. It is the sound quality evaluation method that appears to make up for the defects of A sound pressure level. It takes the features of the auditory into consideration and can accurately reflect the ear auditory subjective feeling. Currently, sound quality evaluation method is used in passenger vehicles and small electrical appliances and the evaluation index in the field of engineering machinery is given priority to A sound pressure level.The key to solve the noise problem is to give an accurate evaluation. The main index in engineering machinery is to decrease the A sound pressure level. Because the different spectrum characteristics of the same dB noise, the noise causes the different subjective feeling. Then the standard to decrease A sound pressure level as the noise control is not normal. Whether the sound quality evaluation is better than A weighting evaluation or replace it is the main research emphasis in this paper. The paper mainly did the following work:The paper systematically introduced the physiological characteristic of the human ear hearing and psychological characteristic of subjective hearing, introducing the concept of sound quality and gave a deep understanding of sound quality from the perspective of psychoacoustics, and stated the meaning of the parameters of sound quality evaluation.The paper gave an in-depth study of the standard ISO532A Stevens loudness model algorithm and the Zwicker ISO532B loudness model algorithm. Due to checking figure in Stevens model algorithm, it is not easy to programming. According to the Stevens Equal Loudness Contour, figure formula was studied and improved the Stevens chart method, then obtained with MATLAB programming platform. Algorithm in this paper explores the informally given magnitude in Zwicker loudness model, and deduces the replacement quantity, making the Zwicker loudness model more complete and detailed.The paper designed the subjective evaluation experiment using the noise of excavator and bulldozer as the experiment object. Through the discussion on the subjective experiment method, according to the purpose and the feature of this experiment, select method of paired comparison as the main subjective evaluation method. At the same time in order to make the subjective results more accurate, this article designed the evaluation of different broadcast order samples and improved the subjective experiment on the basis of paired comparison.Finally, this paper compared the A weighting sound pressure level、sound quality value and the subjective test results, the analysis shows that:In the engineering machinery noise, the sound quality evaluation can reflect the human auditory perception better than A weighting sound level. The paper attempts to evaluate the engineering machinery noise using sound quality evaluation and attained the better results, providing a new method of sound quality evaluation and improvement in engineering machinery field.