Thanks for reaching in Roku Community!
We are sorry to hear that you are facing voice/sound issues while trying to watch the Amazing Facts channel. To clarify, does the issue only occur on this specific channel or all channels on your Roku device? Have you tried to remove the channel and see if it helps? If you haven't tried it yet, you can remove the affected channel and re-install it. To ensure the process is successful, restart your device before adding the channel back in. We would recommend doing this from the Settings menu by navigating to Settings > System > System restart.
To help you further troubleshoot, refer to the Support links below:
How do I resolve channel playback issues?
What to do if you do not hear sound from your Roku® streaming player
If the issue remains unresolved after the suggestion above, videos from other channels play fine, contact the channel provider's customer support team to report the issue and get help. Channels on Roku are maintained by the channel developer themselves. In this case, there's likely an issue within that specific channel that needs to be addressed with an update from the channel developer.
Keep us posted on how it goes.