Patent GB-124804-A (GB)
Title: A Method of and Means for Determining the Direction from which Sound Proceeds, and the Distance at which it Originates.
Inventor: MUNRO HUGH
IPC: G01V1/00
Filed: 1916-04-10
Abstract: 124,804. Munro, H. April 10, 1916 Locating sounds. - Apparatus for determining the direction of a source of sound, and, if required, its distance, comprises one or more pairs of receivers and means for determining when the sound reaches both receivers of a pair in the same phase. Fig. 1 shows two open-ended bell-shaped receivers 1, 2 mounted on a frame 3 rotatable upon a vertical axis 4 and connected by tubes 9, 10 with a listening tube 8. To find the direction of the source of sound, the apparatus is rotated about the axis 4 until the effect in the tube 8 is a maximum or minimum, the direction being indicated by a pointer or equivalent. The receivers may be tuned by slidable sleeves 5 or slidable U-tubes 11, and shields 6, 7 may be provided to increase the directive effect. Any suitable means may be used to detect phase-agreement. In a modification, Fig. 2, the receivers 12 are cylindrical and are closed by perforated diaphragms 15 and tuned by pistons 17. The sound is led to opposite sides of a diaphragm 17<a> which is unaffected when the sounds are in phase. Vibration of the diaphragm may be detected by a microphone connected to a battery and telephone receiver, or by optical methods. In a further modification, the rear ends of the receivers are closed by plates provided with tunable vibrators carrying reflectors and adapted to vibrate about perpendicular axes. A ray of light reflected from the two reflectors in turn falls upon a screen, and the form of path traced by the light spot enables determination of phase-agreement. The Provisional Specification 9076/16 describes the use of prisms instead of reflectors. In another form, the receivers have diaphragms vibrating in the magnetic fields of electro-magnets. Secondary coils mounted on the electro-magnets are connected together through a suitable current indicating or measuring instrument. The currents induced in the secondary circuit due to vibration of the diaphragms give a maximum or minimum reading when the sounds are in phase-agreement. In a further modification, the receivers are formed as narrow chambers separated by a plate. To determine direction in two planes at right-angles, two or more pairs of receivers, rotatable about perpendicular axes, are used. A form of apparatus for finding the distance of the source of sound has two pairs of receivers mounted in line, one pair being rotatable with reference to the other about an axis perpendicular to this line. The distance is to be calculated from the known distance between the pairs of receivers and their relative inclination when directed towards the sound source. According to the Provisional Specification 5202/16, a diaphragm carrying two microphones, one at each side, is used. The plane of the diaphragm passes through the source of sound when the microphones are equally affected. Two such diaphragms rotatable about perpendicular axes may be used, or two intersecting diaphragms fixed together at right-angles with pairs of receivers in alternate angles. Or a microphone may be mounted in a passage through a main diaphragm, and protecting-diaphragms may be placed on either side of the main diaphragm, the three being connected to vibrate in unison. The apparatus may be used for locating sounds in air, water, or ground. In the last case, the apparatus is placed in a sunk reservoir containing gas or liquid. Reference has been directed by the Comptroller to Specifications 4152/09 and 26774/10.