Abstract: new diagnostic method based on the two microphone cross spectral acoustic intensity technique was applied to identify the cabin noise source paths The simulating test using a loud-speaker and an electro-mechanical shaker to simulate the airborne and structureborne noise sources was conducted to prove the confidence of the proposed method The results show that the discrepancies between measured and separated values of total average acoustic intensity level are respectively 1.7dB(A) and 0. 4dB(A)for structureborne and airborne components,which is acceptable for engineering application. The static test with engine in operation shows that the airborne noise through the rear board of cabin is the dominant contributor to cabin noise.This is a reasonable result,which gives a guide to cabin noise control treatment.

Key words: sound transmission, acoustic measurement, light aircraft