Patent GB-164091-A (GB)
Title: Improvements in and relating to sound locating apparatus
IPC: G01S1/72
Filed: 1920-02-25
Abstract: 164,091. British Thomson - Houston Co., Ltd., (General Electric Co.). Feb. 25, 1920. Locating sounds.-A compensator for soundlocating apparatus, in which the direction of a source of sound is estimated by the binaural offect consists of two co-operating discs rotatable with relation to each other, the upper one provided with concentric grooves 31, 32, Fig. 2, joined at their ends 33, and the lower with two projections 35, 36 which fit into the grooves and divide them into separate U-shaped paths along which the sound travels to the ears of the listener. Three sound collectors such as inertia microphones a, b, c, Fig. 14, not in a straight line are employed and any two can be connected to the telephone receivers 49, 50. The sounds from these receivers pass through the compensator 27 to stethescope nipples 45. The compensator is shown in trarsverse section in Fig. 2 and vertical section in Fig. 3. It is mounted in a cup-shaped casing 23 set into the lid 21 of a box and consists of two discs 26, 28 of which the upper one can rotate over the lower by means of a centre post 27 and a hand-wheel 29. Inlet holes 37, 38 and outlet holes 39, 40 provide two air paths, and by rotating the upper disc the relative length of the paths is altered. Where a greater range is desired several pairs of grooves may be used. To adjust the clearance between the two discs the upper one rests on a ball bearing 46 and all or part of its weight can be carried by the ball by adjustment of a screw 47. A casting 41, Fig. 3, is fixed to the bottom plate and contains inlet passages 42 and outlet passages 43. A tubular relief vent, 2 inches long and # inch bore is provided which it is stated relieves pressure variations owing to the changes in lengths of path without modifying the sound waves. The transfer switch to connect any pair of transmitters with the apparatus consists of an upper ring with three insulated segments 51<a>, 51<b>, 51<c>, a middle ring 52 connected to one receiver, and a lower ring 53 connected to the other receiver. Brushes 54, 55 for connecting the segments to the middle ring and brushes 56, 57 for connecting the segments to the bottom ring are mounted on brackets 58 of a brush-holder ring 59. The brush-holder ring is turned by a handle above the bore cover which besides indicating which pair of transmitters is connected to the compensator moves a cover to expose the scale of bearings appropriate to that pair. The three segments 51<a>, 51b, 51<c> are connected through condensers to brushes 66a, 66<b>, 66c, Fig. 14, and through reactances to the common terminal of two batteries 68, 69 either of which may be used. The plug 77 has an insulated conducting sleeve 78 and three insulated rings 79<a>, 79<b>, 79<c>. The transmitters a, b, c, have each one terminal connected to the rings 79a, 79b, 79<c> respectively, and the fourth common terminal is connected to the sleeve 78. The microphone not being used is connected through a resistance or inductance equal to that of the receiver by means of a brush 82 on the brush-holder ring. Reference has been directed by the Comptroller to Specification 146,192.