If you combine a smartphone and a smartphone wristband, you can create a speech tool for the hard-of-hearing and the mute. To make it, juts put a smartphone in a smartphone wristband. You can even use it as a translator.
HARD-OF-HEARING
Download a Text-to-speech app and enable speech-to-text with a notes app. Use the Text-to-speech app for talking, and the speech-to-text for "hearing".
NON-VERBAL AUTISM/MUTISM
Download a Text-to-speech app. Use the Text-to-speech app for talking.
TRANSLATION
Download a Translation app. Google Translate is good for this. Make sure to download relevant languages.