Respondus Monitor is designed to only record ambient sound. The pre-exam webcam check includes a step where the student can ensure that the audio is recording properly.
Monitor should not be used to record an audio response to an exam question.
However, if your exam question has an audio response recorder built in (such as to allow a student to record an answer for a foreign language class) then faculty need to take advantage of an advanced setting in the LockDown Browser Dashboard. This setting is titled "Allow another application to use the microphone during this exam."
Once this setting is enabled, ambient sound won’t be recorded by Respondus Monitor during the exam because it must release the microphone to the other application.