Pressing Ctrl+B toggles the Text To Speech function to the opposite of whatever setting is chosen in the Audio settings UI, but it doesn't change the setting in the UI. As a result, pressing Ctrl+B always results in either "Text To Speech enabled" or "Text To Speech disabled" no matter how many times you press it. The only way to toggle it back is to go to Audio settings and toggle it there (twice, because it was already out of sync with the actual state).