How to add sound to amateur films (1954)

of the question, since no optical sound projectors are available for that gauge. Let us therefore look at the different systems in more detail. Disc Recordings The process of recording and reproduction is exemplified in the familiar gramophone record. A device very like a gramophone pick-up cuts a wavy groove in a lacquercoated disc. Each electrical pressure variation produces a corresponding vibration of the cutting needle. The record you buy is a perfect copy of the lacquer original, but made in much harder material. When you play this record with a pick-up, the needle is forced to vibrate to follow the waviness of the groove. The pick-up then transforms the vibrations of the needle into electrical pressure variations which can be amplified and used to operate a loudspeaker. From the point of view of initial cost, it is hard to better the disc system. The majority of households owning a cine camera have also a gramophone and a radio. If these are not already available, they can be picked up quite cheaply secondhand. Once you have built up a library of records, you can readily provide music to accompany almost any film. The process requires the minimum of preparation in advance and costs nothing since the same records can be used for many films. To the ultra-critical, the hiss or scratch of the needle in the groove may be objectionable. Yet whichever system of sound recording we use, this needle scratch will be present if we draw on gramophone records for our music. Fibre or thorn needles considerably reduce the scratch or surface noise. There is another argument in their favour: people are more willing to lend you their records if you can assure them that you use only this type of needle. On the other hand, these needles must be changed frequently and even with twin turntables this is a nuisance. A good quality 41