I using JDeveloper 12.2.1
Given the HTML 5 <audio> tag...
<audio src="myAudioFile.mp3" controls="controls" autoplay="autoplay">
Your browser does not support the audio element.
</audio>
The FireFox browser version 47.0 renders and plays audio successfully...
However the Chrome browser Version 51.0.2704.84 m (64-bit)...
renders but with a slash ' / ' through the speaker and does not play audio.
In JDeveloper, use TOOLS | PREFERENCES | WEB BROWSER to set your browser
to Chrome and give this a try.
OH, MAKE SURE YOU HAVE NO ADDITIONAL PLUGINS or deactivate / disable them
before giving this a try.
Can HTML 5 <audio> tag Play on your Chrome browser ?