In fact, it's very easy to change the default audio player from VideoJS player (Moodle's default) to the HTML5 audio player:
- Go to Site administration / Plugins / Multimedia plugins / Manage media players and move 'HTML5 audio' above 'VideoJS player'. See the screenshot below.
Note, however, that this change will apply to your entire Moodle site. If you want to keep VideoJS as the default player while using HTML5 audio in specific activities or resources, or if you do not have access to site administration, you can use the script I gave above.
Moodle 3.2 now comes with a default industry-leading media player - Video.js:
