DIRECTIONAL MICROPHONE

摘要

A directional microphone is disclosed which comprises a microphone array (3) having a plurality of microphone elements (4,5,12,13) of which the element (4) is a rear element and the other elements are forward elements. A processor (19,31) is connected to the elements. The processor can be a hardware processor for processing signals or it can be a software controlled system for processing signals. The processor determines the arrival of a wave at one of the forward elements (5,12,13) and thereafter establishes a window of opportunity for receipt of the wave at the rear element (4). The window of opportunity is set such that only waves emanating from a particular direction will arrive in that time frame, thereby enabling acoustic waves from that direction to the processed by the microphone and other waves from different directions eliminated. The angle of arc of the microphone from which acoustic waves are received and processed can be set by changing the size of the window of opportunity t3-t2. In the hardware implementation, the processor includes filters (21,22), zero cross-over detectors (23,24), monostables (25,26) and flip-flop (28) for setting a timing signal and triggering the flip-flop (28) to control the switch (29) so that if a wave does arrive at the element (4) within the bandwidth of the filters (21,22), an audio signal corresponding to the wave is transmitted from the element (4) through the switch (29) to an output (30).