Google meets.
It is highly recommended that you always check your camera speakers mic and connection to be sure all is working before you start you Presentation.
Log into you google account
go to your email.
go to start a new meeting. located on the left of your email screen.
Click NEW MEETING
New box will appear.
Click Join now
New box wil appear
Click Check audio video
New window appears
Be sure correct Mic, Speakers and camera is selected.
Click that audio icon in the box 
You should hear a sound. This is quick way to be sure sound is working.
Click on NEXT
New screen will appear
Click Next to start the test of mic, audio and speakers
new Screen will appear
You should get a camera image and google will ask you to say something to test the mic.
It will record a short clip to be sure you system is working. Say a few words.
New screen will appear.
You will see check marks of all detected and a replay of you video to be sure you video and audio and mic work.
Once you hear it and see the video your equipment should be working.
If not check all cable connections and click check again to try again.