Speed on spoken text
Spoken language uses short words, contractions and commas, and that rhythm differs from formal writing. Practicing it makes audio work feel less frantic, because you're not slowed down by the text itself.
Copy test vs. audio test
This is a copy test. Many transcription jobs also test audio typing or transcription accuracy against a style guide. Ask what format the employer uses.
Next steps
Try the medical or legal passages if you're aiming at a specialty, and read how to pass a typing test.