Abstract: A sensor (1) including at least one array (10), including a plurality of acoustic transducers (12); a controller (42) for controlling each transducer (12) to be selectively in a generation mode for generating an analysis signal, or a reception mode for receiving an analysis signal, and, for controlling the sensor (1) to perform scans of the at least one array (10), each scan having a plurality of scan steps, such that, during each scan step, at least one transducer (12) is in the generation mode and at least one other transducer (12) is in the reception mode; and, a processor (44) for processing one or more signals receivable from one or more of the controller (42), a transducer (12) in generation mode and a transducer (12) in reception mode to determine at least one characteristic from the one or more signals.