It used to be a dream to imagine being able to ‘see the sound’, but you can do exactly that with this system from GFaI in Berlin. Using an array of microphones, with a patented camera, the system uses a beam-forming technique to locate the sources of sound, and create an image superimposed on an optical image taken at the same time.
The acquisition is high-speed, meaning that quick images can be taken live or longer ‘exposures’ reveal more detail and allow post-processing.
Several arrays are available, depending on frequency range and size of source. For example, the Star array uses three large arms to space the microphones for large environmental sources such as wind turbines or factories. The general purpose array is best for measurements on car engines, or computing devices, and there’s even a small array for measurements on devices like mobile phones.
The software is amazingly intuitive, with images popping up within seconds of acquisition, and in-built frequency analysis allows you to home in on hot-spots of sound radiation.
The system can also take ‘acoustic movies’ so you can watch how the sound changes as the source moves. For example, this is very useful for vehicle pass-by, or sources which change with time. You can even visualise the radiation of noise from the tips of a wind-turbine as it goes round!
The software also works in 3-D with a special array, so you can see the radiation of sound from complex surfaces. This is a key application inside car cabins, locating the source of squeaks and rattles within seconds.
Extensions include order analysis for rotating machines, and you can also playback the noise from individual ‘acoustic pixels’ to understand the contribution of different source levels.