Sound levels in closed cavities, such as on the command bridge of a military boat, are in many cases unacceptably high in terms of comfort and the sound environment. To be able to determine which means of sound reduction should be applied, it is important to have a good understanding of \ the origin of the sound field, and especially which parts in the cavity that have the highest sound levels. Today's hardware can handle large amounts of data. Therefore, a method using a large number of microphones is a good alternative for sound intensity measurements. Such a method has been used in this project. The method is evaluated on a Swedish minesweeper with a microphone matrix that consisted of 730 microphones positions, using 32 microphones at a time. The sound measurements are processed on a software platform via a dataacquisition system. This paper presents the background to the sound problem, the data collection and the analysis. Several sound plots will be presented on total sound levels and narrowband analysis, with conclusions on key sound sources etc. Conclusions on the experiences from this large measurement project will also be drawn.