GB1054796A - - Google Patents

Abstract

1,054,796. Microphones. PHILIPS ELECTRICAL INDUSTRIES Ltd. Sept. 2, 1963 [Sept. 5, 1962], No. 34595/63. Headings H4D and H4J. A microphone combination comprises a pair of microphones 1, 2 spaced from one another and from an obstacle 3 placed on the line a joining the microphones 1, 2. The microphones 1, 2 are such and so connected that a sound wave of identical characteristics arriving simultaneously at each microphone provides a substantially zero output signal whilst the obstacle 3 is such that, for sound reaching the microphones 1, 2 from a source 5 on an extension of the line joining the microphones, the path length from the source 5 to the microphone 2 more remote from the source 5 round one side of the obstacle 3 is different from that round the opposite side of the obstacle 3. A more even frequency/sensitivity characteristic is obtained with the obstacle 3. The microphones may be identical cardioid microphones facing the same direction. The obstacle 3 may be a circular plate, an ellipse or a rectangle. Alternatively, the obstacle 3 is a solid of revolution. The obstacle 3 may be provided with a sound-absorbing layer on the soundincident side. A plurality of pairs of microphones may be provided substantially on the same line with an obstacle between each pair (Fig. 5, not shown). The microphones, particularly when in the form of microphone columns, may be angled with respect to each other (Fig. 7, not shown).