The optophone is a device, used by the blind, that scans text and generates time-varying chords of tones to identify letters. It is one of the earliest known applications of sonification. Dr. E. E. Fournier d'Albe of Birmingham University invented the optophone in 1913,[1] which used selenium photosensors to detect black print and convert it into an audible output which could be interpreted by a blind person. Barr and Stroud participated in improving the resolution and usability of the instrument.[2]
Only a few units were built and reading initially exceedingly slow; a demonstration at the 1918 Exhibition involved Mary Jameson reading at one word per minute.[3] Later models of the Optophone allowed speeds of up to 60 words per minute, though only some subjects are able to achieve this rate.[4]