MT$ on Mobile 5 - CHIME?

 
Hello,

Using MT4 on a TREO 700WX with Mobile 5...

When I'm in the chart window, occasionally the CHIME goes off... what exactly does this chime indicate? It looks like a "new low or high for the bar"... but not sure. Is there a way to disable this? (Can't have the chime go off while in a meeting...)

So far, I am really enjoying this wireless plateform....

Thanks for the help!
-charliev