[imp] New mail won't play a sound

[Michael Wing]

I'm running Horde Groupware Webmail Edition 4.0.8 with Imp 5.0.22.  I have
my new mail preferences configured to play a sound when receiving new mail.
 I can see the notification pop up, but no sound is ever played.  I can
test the playing of the selected sound in the preferences, and it plays
fine there.

Can anyone provide some troubleshooting assistance for this?

Thanks,

Michael