iOS 11.0.2 is now available. See below from Apple' site:
iOS 11.0.2 includes bug fixes and improvements for your iPhone or iPad. This update:
For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222
I don't have an iPhone 8 or iPhone 8 Plus but let us know if this fixes the "crackling sounds"