Automatic start audio does not consistently start automatically when using the Safari browser.However, it always plays automatically with the chrome browser.

The issue appear to occur for database activity text entries for student user using Safari at https://school.moodledemo.net. It works for instructor user on Safari, or at least the one who added the entry.

Replication:
1. Create a course.
2. Enrol instructor and student users.
3. Turn edit mode to On.
4. Add a Database activity.
5. Go to the Database activity, use preset and select Journal.
6. Go back to the activity and "Add entry".
7. Under the content +ATTO HTML +textbox, select media picker icon. "Insert media"
8. Select Audio and upload an MP3 audio file. Tick Show controls and Tick Play automatically.
10. While on edit mode, you can see the audio control is displayed and plays automatically.
11. Click Save.
12. Log in as the student user and navigate to the database activity.
RESULT: The audio file does not play.

Note - Sometimes the audio does work if the screen is refreshed or the activity is opened and closed again but for the majority of test cases it does not work.
It works for instructor user on Safari, or at least the one who added the entry.