**Abstract**

Airborne sound insulation in buildings, whether in fixed partition elements, like partitions or party walls, or mobile elements, like doors or screens, is always related to the performance of the weakest element involved. In situ assessment of airborne sound insulation in building elements can be carried out by pressure techniques or sound intensity techniques. Sound pressure techniques are very quick but fail to discriminate the sound insulation contribution of each building element involved. Sound intensity techniques, on the other hand, allow to determine the sound transmission of each element and also to discriminate indirect transmissions up to a certain degree. In order to find areas with high sound transmission, such as leakages or weakened regions, a large number of measurements on the building element surface have to be performed. Moreover, the sound intensity technique is very timeconsuming, because it is necessary to carry out the measurement in each grid point defined. This chapter describes the use of beamforming and SONAH techniques to detect areas with lower airborne sound insulation in a building element. These techniques unify the advantages of both, pressure and sound intensity techniques, allowing the quick visualization of leakages or weakened areas of different building elements.

**Keywords:** building, insulation, leakage, SONAH, beamforming
