This paper presents the results of a vibro-acustic investigation carried out in a vehicle gearbox. The investigation consisted of modal analysis, measurements of insert loss and acoustic efficiency of the housing. A high insert loss was measured showing that the air-borne noise contribution can be neglected. On the other hand, the acoustic efficiency values for the gearbox housign show that the vibration characteristics of the structure have an essential influence on the structure-borne noise and noise radiation from the gear housing.
