Which Office program are you using?
Cause: The microphone is not connected correctly to the computer.
Solution: Check your connections.
For each computer being used in the conversation, check the connection between the microphone and the computer.
If the microphone is integrated with the webcam, make sure that the webcam is connected correctly.
Cause: Sound is muted or turned down low in the conversation window.
Solution: Check the settings in the conversation window.
In the conversation window, make sure that Mute is not selected.
In the conversation window, make sure that the volume slider is not set too low.
Cause: Sound is muted or turned down low in the Mac OS settings.
Solution: Check settings in System Preferences.
On the Apple menu, click System Preferences.
Under Hardware, click Sound.
On the Input tab, make sure that the correct device for sound input is selected.
To see whether the microphone is working, speak into the microphone. You should see movement on the Input level display. Adjust the Input volume, if necessary.
On the Output tab, make sure that the correct device for sound output is selected. Also make sure that the volume levels are not too low and that the Mute check box is cleared.
Obs!: For more information, see Mac Help.