If you don't like the externally-downloaded voice, you can use a recording app on your device to record the 'system' or 'internal' sound while you're playing the generated voice audio.
You can download the audio as a file, but note that the downloaded voices may be different to your browser's voices because they are downloaded from an external text-to-speech server. This web app allows you to generate voice audio from text - no login needed, and it's completely free! It uses your browser's built-in voice synthesis technology, and so the voices will differ depending on the browser that you're using.
