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Stereophony on Trial.

Wireless World, February, 1959.
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For more than a quarter of a century the subject of stereophony has been debated in the pages of this journal. Much of the argument in the past has of necessity been of a theoretical and speculative nature, but since the introduction of stereo tape and disc records and of experimental two-channel broadcasting by the BBC it has been possible to refer hypothesis to the arbitration of experiment. Far from settling matters, this seems so far to have engendered fresh and even more vehement argument.

We think it likely that a public opinion poll conducted at this stage would find roughly equal numbers 'for' and 'against' but a far larger entry in the 'dont know' category.

Those 'for' would unquestionably include all who have been privileged to hear stereophonic reproduction in the research and development departments of the leading recording companies and of the BBC, under controlled conditions and with the best of equipment, regardless of cost. It would no doubt also include those who were fortunate in their choice of demonstrations at the Audio Fair and the Radio Show.

Among those 'against' would be found the less fortunate in their choice of demonstrations, who may be forgiven for regarding the whole business as a 'gimmick' to promote sales; also many 'hi-fi' enthusiasts who are loath to admit that their single-channel equipment, on which they have recently spent large sums of money and which they regarded as the ultimate in performance, is capable of improvement. Some find the enveloping effect of stereophony tiring or even mildly claustrophobic, though they are not so affected by the multiple reflections, by the walls of the room, of the sound from a single loudspeaker. This is understandable, because the listeners aurally conditioned reflexes - the result of past experience - and the activity of his imagination are important factors influencing his judgment. Whatever the system, the sounds presented to his ear are a complex from which he can accept or reject only a fraction of the available clues to build up his perception of the information conveyed. Many people find all they need in the sound resulting from the skilfully employed microphone techniques of single-channel broadcasting and recording. The aurally literal and less imaginative welcome stereophony as an obvious necessity.

The 'dont knows' include many far from 'clueless' individuals who derive real enjoyment from single-channel sound, supplemented perhaps by individual methods of dispersal by reflection or the use of multiple speakers. They find good stereophonic demonstrations equally satisfying but not obviously superior, and understandably hesitate to incur the expense of revising and adding to their equipment. Hitherto no means has been available for comparing single-channel with stereo by a direct switch-over. Test records which merely switch off one channel would be obviously useless and paralleling the outputs of microphones placed for two-channel stereophony must always give poorer results than those obtained when there is complete freedom of choice of characteristics and position for the best single-channel balance. The only fair test is a comparison of simultaneous reproduction through single-channel and separate stereo channels, each system using its own microphones placed in the optimum positions, regardless of the technique being employed in the other system. Separately recorded disc records are possible, but might meet with synchronization difficulties on playback. Simultaneous recording on three tracks of a magnetic tape would be better but would require special apparatus. Broadcasting is obviously the best medium for tests of this kind and the BBCs experimental 'live' stereophonic broadcast of January 24th, although not intended for this purpose, could have been so used. The closely spaced stereo microphones supplying the Network Three and TV sound channels were introduced and used separately from the normal microphone arrangement used for the regular single-channel broadcast of 'Saturday Club' which went out as usual on the Light Programme.

A final appraisal must await the initiation of a regular broadcast service which, among other things, may depend on some modification of the two audio channels to make them 'compatible' and capable of being broadcast through a single transmitter. Now is the time, however, to start to reduce the ranks of the 'dont knows' by presenting for their choice a clear comparison of the best single-channel technique with the best stereophonic reproduction.

Although many high-quality enthusiasts have enough gear lying around to mount this experiment for their own satisfaction, the onus of demonstrating to the public at large must rest with the more enlightened dealers - and, of course, with the BBC on whose continued co-operation the success of such tests must ultimately depend.

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