This video explains Super 8 Sound and Video Cameras pretty well. Only super 8 had sound but not just regular 8mm movie cameras.

https://www.google.com/search?q=what+does+super+8+audio+film+look+like&rlz=1C5CHFA_enUS750US750&oq=what+does+super+8+audio+film+&aqs=chrome.1.69i57j33i22i29i30l4.8187j1j7&sourceid=chrome&ie=UTF-8#kpvalbx=_CKbbYbKADpSq0PEPir-5CA41