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Design of a simple reading machine for the blind

University of British Columbia

A compact reading machine ("Lexiphone") has been designed and constructed to convert printed letters into a pattern of sounds. The machine reads by direct translation of vertical sections of the letters, according to a recently developed code. In this code, the "melody" produced is independent of the vertical position of the reading head ; however the user is given an indication (mean pitch) of the vertical position to-facilitate tracking along a line of print. The discrete nature of the direct translation process limits the theoretically possible reading rates. Tests with artificially generated codes were performed to investigate this limit, and it is expected that the limit will be above that for Morse Code-- 60 to 70 words per minute. This would be adequate for practical use. Tests performed at Haskins Laboratories predicted similar performance for other machines, such as the optophone⁽⁴⁾. However, practical users of the "Battelle Optophone", the most refined version of the optophone, attained only 25 words per minute (on Grade I reading material) after an extensive course⁽⁸⁾ . It is suggested that this was due to the difficulty in the earlier machines of producing repeatable versions of the code. Code sounds from the present Lexiphone prototype were found to be very consistent and repeatable, and should allow the predicted reading rates to be approached. Practical reading results with the machine are presented. At the time of writing, a subject training with the machine is reading two-page passages of Grade III material at 30 words per minute, and her performance is still improving.

Text

2011-06-07

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http://hdl.handle.net/2429/35275

Electrical and Computer Engineering

University of British Columbia

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