Frequently Asked Question

Speakers

Go to Apple Menu > System Preferences > Sound > Output
Make sure that your internal speakers are selected (name may vary)
Make sure that your output volume is not muted or turned all the way down

Microphone

Go to Apple Menu > System Preferences > Sound > Input
When you speak, the input level should fluctuate as it picks up sound
Make sure that your input source is your internal microphone (name may vary)
Make sure that your input volume is not turned down all the way