For a first game, this is fantastic. Well done. However,I have some suggestions:
1. There is no point including words that sound the same as people will likely get confused if there is no context, and far too few speech synthesizers differentiate them adequately.
2. The initial speed is too slow, so perhaps you could include a setting that chooses how fast the initial speed is.
3. For longer words, you could give just a little more time for people to type them.
4. As soon as a person gets a word wrong, you could make an error sound before the next word is announced.
5. For the music, perhaps you could include a few different music tracks for people to choose from.
6. Like another person has already said, screen reader support would be nice.
7. It would be nice to be able to fix misspelled words if we know they are wrong.
This being said, this is a great game and I hope that you release more great games in the future.