Abstract: During the development of air-conditioning products, there are some abnormal noise problems,such as wind howling, motor electromagnetic noise, etc., which greatly affect the user experience and the improvement of the sound quality of the product. This paper studies the howling noise of air conditioner indoor units by comprehensively using noise filter diagnosis, acoustic brush scan test and acoustic vibration comparison to identify the noise source and noise transmission path of the howling noise. Firstly, the noise filtering sound diagnosis method was applied to identify the frequency band distribution of abnormal noise; then research the acoustic brush noise source recognition technology based on the combination of sound intensity method and optical tracking technology, and identify that the howling sound is due to the DC brushless motor electromagnetic noise; finally, it was determined that the abnormal noise was caused by the vibration radiation of the motor body through the comparison of the core components.

Key words: Sound brush, Sound source recognition, Filter diagnosis, Spectrum analysis