The impact of alphabet supplementation and word prediction on sentence intelligiblity of electronically distorted speech

Alphabet supplementation is a low-tech augmentative and alternative communication (AAC) strategy that involves pointing to the first letter of each word spoken. Sentence intelligibility scores increased an average of 25% (Hanson et al., 2004) when speakers with moderate and severe dysarthria (a neurologic speech impairment) used alphabet supplementation strategies. This project investigated the impact of both alphabet supplementation and an electronic word prediction strategy, commonly used in augmentative and alternative communication technology, on the sentence intelligibility of normal natural speech that was electronically distorted to reduce intelligibility to the profound range of <30%. Results demonstrated large sentence intelligibility increases (average 80% increase) when distorted speech was supplemented with alphabet supplementation and word prediction.