Hi pratyusha, in case you are still having problems with the volume or quality of voice recordings in your lessons, please try using the Audio Diagnostic Tool. This tool comes with Little Reader, but you can still use it to fix sound problems in Little Math -- you may access the tool outside Little Reader by going to Start > All Programs > BrillKids > Support Tools.
You may refer to this article for detailed instructions:
http://support.brillkids.com/entries/20433747-how-to-use-the-audio-diagnostic-tool