Practical Application of Orthogonal Beamforming

A very important aspect in the process of machinery noise control is the proper identification of noise sources. One of the more recently developed options to do this is the beamforming technique using a microphone array. With this technique, it is possible to localize and rank sound sources. However, there are some limitations with beamforming that may become problems for the practical application of the technique. First of all, due to the limited dynamic range it is not possible to detect minor sources with a level well below the main source. A second problem is the limited spatial resolution that will not allow to separate sources situated closely together. These problems are addressed by an advanced signal processing method, the orthogonal beamforming technique. After a brief overview of the theory of orthogonal beamforming, the focus is on the practical application of the technique. Examples of measurements on machinery and on vehicles are presented and the results are compared to that of the classical beamforming technique.