Audio delay

Jorma is right. Best prictice is: Don't let students participate with speak unless they have a headset.

John K.

The reason you hear your voice 1-2 seconds after you talk is because someone in your meeting has speakers on their computer and has their mic turned on. So your voice comes out of the speakers, then into their mic and back into your ears. Have the other people in the room turn off their mics unless they are talking and that should solve your problem.

Jorma@RealEyes

You need to mute the microphone in the audio settings on the soundcard on your PC.

To do this under XP, right click on the sound icon in the task bar - select adjust audio properties - select the third tab along 'Audio'.
Select Volume under Sound Playback and tick the mute box under microphone. If the microphone is not visible, select the Volume button again and choose options - properties and select the microphone, this will then bring in the option to mute this device.
Ta
Kevan