If you have a Mac and cannot hear the other person, the problem may be due to the “Wave” component of the volume settings of your computer. You can try adjusting this volume settings on your computer using the “Advanced” option in the Audio section of your computer’s operating system.
To ensure that your Mac computer is producing sound:
a. Click System Preferences > Sound
b Click Sound Effects then double click on an effect
c. Select "Play sound effects through" Internal Speakers
d. Adjust Output volume as needed
e. Make sure "Mute" option is NOT checked
If your Mac is still NOT producing Sound:
a. Go to Mac HD > Applications > Utilities.
b. Double-click on Audio MIDI Setup.
c. Change the default audio input from 96,000Khz 2ch - 24bit to 44,100Khz 2ch - 16bit.