A Voice-Activated Switch for Persons with Motor and Speech Impairments: Isolated-Vowel Spotting Using Neural Networks

Severe speech impairments limit the precision and range of producible speech sounds. As a result, generic automatic speech recognition (ASR) and keyword spotting (KWS) systems fail to accurately recognize the utterances produced by individuals with severe speech impairments. This paper describes an approach in a simple speech sound, namely isolated open vowel (/a/), is used in lieu of more motorically-demanding utterances. A neural network (NN) is trained to detect the isolated open vowel uttered by impaired speakers. The NN is trained with a two-phase approach. The pre-training phase uses samples from unimpaired speakers along with samples of background noises and unrelated speech; then the fine-tuning phase uses samples of vowel samples collected from individuals with speech impairments. This model can be built into an experimental mobile app to act as a switch that allows users to activate preconfigured actions such as alerting caregivers. Preliminary user testing indicates the vowel spotter has the potential to be a useful and flexible emergency communication channel for motor- and speech-impaired individuals.