A novel sonic weighing system for the blind

A novel system of weighing articles, which can be used by totally blind persons, is described. The weighing balance is based on the acoustic effects experienced by a membrane under tension and subjected to sonic radiations. The detection of the balance point for a given weight is provided by a sharp change in the sound level at a specific frequency, dependent upon the loading weight.Weighing operations, i.e. (i) weighing an unknown sample and (ii) weighing a material to a predetermined weight, are discussed. Subjective tests have been performed by various individuals, showing fairly consistent results, the greatest deviation being 3 per cent.The scope and socio-economic aspects of the device are also discussed.