If you can't hear sound on an audio or video step, please start by checking your computer is correctly playing sound from other sources (such as YouTube or similar).
If it is, then check your volume level in FutureLearn player controls. To do this, hover your mouse cursor near the speaker icon in the player. A horizontal bar should appear to the left of the main video progress bar.
Please drag the volume slider to the right to set it to maximum, as below:
If you're still having trouble with the audio, all audio and video hosted on FutureLearn should come with subtitles and transcripts on site and in a downloadable PDF. You can learn more about how to access these here: Subtitles and Transcripts
You can find other troubleshooting advice for audio and video on FutureLearn here: Problems with video or audio on FutureLearn