Lee Ann Dickerson mentioned in her webinar this evening about transcribing lectures for our students and for accessibility. Google voice typing is what she recommended. Here is a link to Google's Chrome extension for voice in voice typing:
https://chrome.google.com/webstore/detail/voice-in-voice-typing/pjnefijmagpdjfhhkpljicbbpicelgko?hl=en
Another option would be to type your voice directly in Google Docs and Slides:
https://support.google.com/docs/answer/4492226?hl=en