Voice annotation lets you insert an audio recording. You can access it via using the 'Comment' tool.
After selecting the text that the comment will refer to (or dot), you can create an audio comment by selecting the microphone button on the right side of the comment box. Press once to begin the recording, and again to end the recording.
Note: The audio comment feature is unlocked with the purchase of a Teacher/Schools Plan, or a Pro/Work Plan.