These are not really much use - as they are - espically in a busy room.  However what would make more sense is that a sound notification could be heard by someone logged into thye chat room if part of there username is included in text being entered ...

For example - if my username was "superman"

fred> hi everyone hows it going
sexygirl> cool thanks fred - glad it the weekend
sexygirl>hey superman you free tonight or you saving the world lol    #alert played to superman#
superman>lol - no my cape is at the dry-cleaners

on other sites I have seen this work based on the first 4 characters of the username so that you do not need to type out the username is full - perhaps that could be a config setting.
Hope that makes sense - be happy to try and clarify if it doesnt