A microphone array is a microphone network, spread over space with a predefinite geometry. Associated with an array processing method, it becomes a directional measurement system, focusing hearing on a limited source area of a multi-source sound environment.
Microphone arrays are used for acoustic imaging. In order to study vehicle noise sources in real conditions, the array is placed on the side of the traffic lane (road, railway...). The hearing area can be steered with the moving source on a vehicle at pass-by.
UMRAE has several array configurations for locating and characterizing noise sources, including two bidimensionnal arrays:
- a 41-microphone cross-array, made of two perpendicular arms, each being respectively formed of two subarrays of microphones spaced with 15 cm and 5 cm;
- a circular array of 57 or 61 microphones, with a span of 2.56 m, offering a constant spatial resolution over a wide frequency bandwidth.
These arrays are used for assessing the noise emission of road and railway vehicles, on test tracks or on site.