Experimental Study Of Sound Field Reproduction System For Subjective Evaluation Of Vehicle Sound Quality

Subjective evaluation of vehicle sound quality is an important step to improve theperformance of vehicle sound and vibration. In order to improve the effect of subjectiveevaluation on sound quality，and make evaluators have a better experience duringevaluations, which will help them make a more scientific and precise evaluation,therefore, research of the methods on subjective evaluation of vehicle sound quality isof great importance.In order to simulate actual vehicle sound inside the laboratory space, first need toestablish a set of theory on sound field reproduction. This paper analyzed thereproduction theories under non-free-field environment, established the model ofelectric-acoustic transfer function in non-free-field, studied the ill-conditioned problemwhen solving the drive signals of loudspeakers, and established a feasible solutionthrough the method of ridge parameter.The testing system of sound field reproduction is the platform to conduct theresearch of sound field reproduction experiment. This paper introduced the way ofconstructing a sound field reproduction testing system with audio and videosynchronized, including the selection of audio hardware and loudspeakers, the layout ofproject equipments and the solution of playing audio and video synchronously.On the platform of sound field reproduction, the research based on a hemisphericalloudspeaker array aimed to reproduce a multi-frequency stable sound field is firstconducted. The measuring method of the electric-acoustic transfer function is studied,and proposed the whole cycle truncation analytical method to improve the computingaccuracy. In order to study the influence of the distribution of sampling array, a planearray and a hemisphere array were used to sample the multi-frequency stable soundfield respectively. The result shows that the hemisphere array is better for regionalsound filed reproduction, the error of overall sound pressure level can be controlledunder1dB.Then, the reproduction experiment of an outside sound field of a vehicle inacceleration condition is conducted. In order to measure electric-acoustic transferfunction in a broadband frequency domain, the method Multi-Speakers Measure Synchronously with Frequency Band Staggered were proposed to improve themeasurement precision and efficiency. Proposed method of Short Overlap Processing tosolve the jump problem when joining together drive signals of loudspeakers. The resultsshows that sound field reproduction have a better performance at frequency domainover100Hz, the overall sound pressure level error can be controlled under2dB.At last, the subjective evaluation experiment which aimed to compare the earphoneplayback system and the sound field reproduction system is conducted. Statistical resultshows that, compared to earphone system, sound field reproduction system have betterperformance on data validity, accuracy and comfortableness of evaluation.