The issue seems to be related to specific hardware as Skype has experienced this as well.
Select a different microphone
The first suggestion is to utilize the Settings menu in the video recorder to select a different microphone.
1. Click Settings in the bottom right of the video recorder.
2. Select a new microphone or re-select the one you're sure you want to use from the dropdown menu.
3. Click "Close".
4. Re-record your answer and see if this resolves the issue.
If the issue persists from question to question, you may need to re-select the microphone before starting each question.
Ensure microphone is plugged in properly (for external microphones)
If you're using an external microphone (one that plugs into your computer,) make sure it is plugged in all the way. If it is partially plugged in, you may experience intermittent audio.