Here are a few things to check:
1) On your LabPad, click on the sound icon, on the top-right: 🔉
2) Check if your computer's sound, maybe it is muted or the sound is very low:
3) Check your browser, when you are playing a video on your browser a music icon on the top right would show up to make sure it is not muted.
If a simulation does not have sound, it will show a message in the beginning. Please note that a few videos on the Faculty Resources page don't have sound either.
Please do not hesitate to reach out to our support team if you have any questions or are in need of assistance.