If this element plays automatically, make sure that there is the ability to pause, stop or mute the audio and the display.
Engine scans for the stop and the pause ability in players. Elements of type <object>, <applet>, <bgsound>, <embed> are automatically suspect to have a such a violation.
Screen reader users should be able to hear the screen reader without other sounds playing. This is especially important for those who are hard of hearing and for those whose screen readers use the system volume.
This also benefits people who have difficulty focusing on visual content (including text) when audio is playing.