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UBC Theses and Dissertations

Towards an improved method of presenting the Lexiphone code and spelled speech Suen, Ching Yee


This thesis describes the effects of dichotic presentations on the reading speed of the users of the Lexiphone - a reading machine for the blind. The dichotic presentations investigated are: a) single delay: one signal to one ear and a delayed version of this signal to the other ear; b) multiple delay: the same signal with three interdelayed versions, two signals coming to each ear. Experiments with the Lexiphone subjects indicated that dichotic presentations (compared with ordinary binaural presentation, i.e. without delay) brought a significant improvement to their reading speed. A similar investigation has also been made on spelled speech which has been proposed to replace the code sounds. The results indicated that multiple delay (as has been found in the case using the Lexiphone subjects) produced a little less improvement than single delay. Nevertheless, both these two dichotic presentations produced an improvement on the intelligibility of the material. The effect of the word length (number of letters contained in a word), on the intelligibility of spelled speech was also analyzed, it showed that the word length has a great effect; it was found that the percent correctness decreases with the word length. This effect also seems to be due to the longer time required to perceive the word from the spelling, thus it is suggested that a longer pause should be provided for those words with a large number of letters. Confusions of some letter sounds were observed when spelled speech was compressed, these are the consonant sounds which are articulated either at the same place or in the same manner.

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