Editorial Notes

Radio Record, Volume VI, Issue 2, 22 July 1932, Page 4

Editorial Notes

Wellington, Friday, July 22, 1932.

-"PHE British Broadcasting: Cor- "~~ poration has been under fire on account of the broadcasting of the -B.B.C. orchestra-the complaints shaving originated: from — several emirient musicians. It is said that the transmissions lack colour and depth, that the technical equipment is at fault, and that the operators are slip-shod. But the facts, so rarely made clear, tell quite another story. a e % PS FEW subjects relating to broadcasting have been more studied than has reproduction. From the inception, engineers have been aiming at perfect reproduction, but even ~ now the listener with the. finest apparatus cannot receive the signals as they originate. The technical factors involved are of considerable interest and emphasise the limitations with which broadcasting engineers have to contend. * % te ‘ SOUND is a to and fro motion of air particles-it may be fast or slow, large or small-and it is this attribute which determines whether the note heard is high or low, loud or soft. There are limits beyond which sounds cannot be heard They extend some way below the lowest note on the piano and a very considerable way above it. A musical note is complex. It is not a single series of vibrations, but a combination of many with the lowest, that from which the note takes its name, pre-dominating. And it is these other notes which make the violin sound different from the piano, the French horn from the cornet. Almost all instruments have a percentage of these upper notes-par-tials as they are called-and if an instrument is to have its full tone all must be reproduced. % e 2 SOUND is such that the degree of loudness affects the tone; loud music, all other things being equal, is truer than soft, Again, a high note leaving its point of origin at the same intensity as a low note sounds considerably louder. The ear, too, is more sensitive to notes in the upper range of the piano than any others. Ifa high and low note are struck simultaneously and at the ‘Same strength, the lower one will tend to obliterate the upper one, the degree to which this takes place depending upon the strength at which both notes are struck or reproduced.

E,XTRANEOUS noises also inter:fere with the quality, and’ even though one may not be directly conscious of it, the rustling of the wind, the crackling of the fire, and the draping of the room, to say nothing. of talking and shuffling, interfere to a greater or lesser degree with the quality. One generally receives a much more correct interpretation from a hall than from the drawingroom. * * a ALL these things tend to alter the characteristic quality of sounds. How much more, then, is this tendency accentuated by broadcasting? * * 8 BETWEEN the listener and the performer is a whole chain of devices and conditions, from the furnishing in the studio to the wind outside the home, that tends to interfere with the quality of reproduction. In any one of these the original notes can be altered beyond recognition, but to these we must pay scant attention, and leave them to the good graces of the designers and operators. We are concerned at the moment with the limitations imposed by well-designed and carefully-operated apparatus. bd & . i : "THE microphone is far from a musical ear, and does not re- spond electrically as the ear does to the brain, so that its position must be different. The balance must be adjusted and the mixture of sound which we pointed out had a tremendous bearing on the quality, must be different right from the onset. bd @ a BUT even supposing this were perfect and could respond: accurately to all notes and combinations, the sounds could not be transmitted faithfully. A transmitting station is required to keep within certain well-defined limits in order to prevent heterodyning neighbouring stations and causing whistles. It is a case of avoiding Scylla to fall into Charybdis, for the faultless transmission of music would cause the station to. deviate far from its allotted path. * % 2 ° FOR adequate separation, stations must be 10 kilocycles apart, but this allows the transmission of only 5000 vibrations (the limit of hearing is 20,000), and all the remain-. der are shut off at the transmission: panel. All those extra vibrations that are so necessary for.. accurate

reproduction are lost, and the music suffers before it has left the station. A cut-off at 5000 vibrations (2YA cuts off at 7000) seriously impairs quality. Approximately one-third of the range of the piano, harp and trombone is lost, only one-fifth of the violin remains, the viola and clarinet are reduced by two-thirds, ' slightly less than half the ’cello, organ, bassoon, trumpet and _ tenor horn have gone, the oboe is spoiled throughout its whole compass, and the human voice is unnatural, Tt may even be unpleasant to sensitive ears. * a e WITH all these shortcomings, the ‘music comes to the receiver. Here -further notes may be cut-off owing to the extreme selectivity of the tuning device or the inability of the speaker or valves to respond to the entire scale. The bass may be accentuated and obliterate higher notes, or it may be lost and allow certain notes almost obliterated in the studio to reappear. The speaker may respond to certain notes more readily than to others-the ear does -and if they happen to be the same the balance is lost. The volume may be cut down and notes, particu‘larly upper ones, playing a minor part in the original may appear out of proportion in the reproduction, and the very draping of the room in which the set is placed may cause accentuation where it is not intended. And none’ of these points take into consideration the commonest cause of distortion found in badlyadjusted or low-quality receivers, or distortion introduced by the listener himself with the tone control. * = * AND so it seems that after all the musical critics of the B.B.C. had something to complain about and the technicians some grounds on which to reply. ‘Y