<P> Five years later, Bell Labs was experimenting with a two - channel Lateral - Vertical system, where the left channel was recorded laterally and the right channel was recorded vertically, still utilizing a standard 3 - mil 78 - RPM groove, over three times larger than the modern LP stylus of the late 20th Century . The trouble with that was, once again, all the low - frequency rumble was in the left channel and all the high - frequency distortion was in the right channel . Over a quarter of a century later, it was decided to tilt the recording head 45 degrees off to the right side so that both the low frequency rumble and high frequency distortion were shared equally by both channels, producing the 45 / 45 system we know today . </P> <P> In 1952, Emory Cook (1913--2002), who already had become famous by designing new feedback disk - cutter heads to improve sound from tape to vinyl, took the two - channel high - fidelity system described above and developed a somewhat misnamed "binaural" record out of it, which consisted of the same two separate channels cut into two separate groups of grooves running next to each other as described above, i.e. one running from the edge of the disc to halfway through and the other starting at the halfway point and ending up towards the label, but he used two lateral grooves with a 500 Hz crossover in the inner track to try and compensate for the lower fidelity and high frequency distortion on the inner track . </P> <P> Each groove needed its own monophonic needle and cartridge on its own branch of tonearm, and each needle was connected to a separate amplifier and speaker . This setup was intended to give a demonstration at a New York audio fair of Cook's cutter heads rather than to sell the record; but soon afterward, the demand for such recordings and the equipment to play it grew, and Cook Records began to produce such records commercially . Cook recorded a vast array of sounds, ranging from railroad sounds to thunderstorms . By 1953, Cook had a catalog of about 25 stereo records for sale to audiophiles . </P> <P> The first stereo recordings using magnetic tape were made in Germany in the early 1940s using Magnetophon recorders . Around 300 recordings were made of various symphonies, most of which were seized by the Red Army at the end of World War II . The recordings were of relatively high fidelity, thanks to the discovery of AC bias . A 1944 recording of Anton Bruckner's Symphony No. 8 directed by Herbert von Karajan and the Orchester der Berliner Staatsoper and a 1944 or 1945 recording of Walter Gieseking playing Beethoven's Piano Concerto No. 5 (with flak fire audible in the background) are the only recordings still known to exist . </P>

Where does the sound originate and how is it produced