An Inexpensive Reading Instrument with a Sound Output for the Blind

An alternative auditory code is suggested to alleviate the reading problem presented by the Optophone in its older form. A ``musical´´ code is discussed which has a high degree of coalescence. Physically it takes the form of an FM squarewave. As for the Optophone, a slit scanner is employed to scan along the line of print. Using Ny photocells, the same number of binary signals b1. . . bn . . . bny are generated by the print patterns. Photocell 1 is located at the bottom of the scanning slit; the cell with n = Ny is at the top. When the cell is over black, bn = 1; over white, bn = 0. Two modulating functions have been used. The first is the familiar binary digit to analog transformation. It is easy to instrument. The disadvantage is the large number of values produced. The second coding function produces fewer f values by discarding information mainly connected with letter thickness. Using either version of the musical code, certain general features in print letters can be recognized. Single straight lines are easy; repeated or symmetrical print shapes, e.g., the letter ``w,´´ are again easily identified. The code is weakest at representing curves. For example, the letters ``o´´ and ``c´´ sound nearly the same. Features used to recognize the lower-case alphabet letters are given. All letters of the alphabet (both lower and upper case) and numbers can be identified by their corresponding code sounds, which are reported to be quite pleasant.