Hi Jackgons,
If your voice is not being picked up, the first place to check will be the microphone settings for your Mac. Change the sound input settings on Mac outlines where these settings can be found, with an option to choose the macOS version you're using in the upper-left corner. The default input should be listed as "Internal Microphone" unless you use a microphone accessory with your Mac.
If that option doesn't appear, there may be a problem requiring further steps or service. Test in safe boot next using How to use safe mode on your Mac along with the subsequent steps depending on the results. If still not working, use Get Support to consult with Apple regarding possible service.
Regards.