The original script by Takuya Kobayashi recently broke since WaniKani changed the URL for the audio. I didn’t see any forum topic that was officially supporting this script, so I made a copy that uses the new URL.
Original description of the script:
Allow audio to be played after review meaning questions, when reading has been previously answered correctly. Also includes setting for enabling autoplay when answer is incorrect (default: off).
New version of the script.