If nothing in the blog helps and the problem doesn't "fix itself" contact the staff directly via Help & Support.
AND describe your OS, browser and ISP when you're looking for help with online problems
http://blog.chess.com/NimzoRoy/diagnosing-and-fixing-internet-problems
Kinghal,
We had an issue where the Android app was doing this -- not making sounds for opponent's moves. We have fixed this in a recent update. If this is still happening for you, and you are using the Android app, please uninstall the app completely and re-install it from the app store. If none of this applies, please let me know. :)
Nope, mine is not Android but a HP laptop.
tarpmaster are you hearing the sounds and then they stop after a couple hours of play, or do you never hear them? Just to be sure, can you hearing sounds on other sites, and do you have your sounds settings enabled for the kind of games you are playing (Live and/or Online Chess)?
Why is it that my opponents' audible move signal in many games does not sound even though my signal is loud and clear? This has been happening on and off for a few weeks. Recently it has started to sound just for a very occasional move.