do i have to use headphones, at this point its practically mandatory
No you don't have to... BUT assuming you mean having open microphone and speakers, and avoiding echo...
- headphones are the easiest, cheapest, simplest, most reliable approach
- could you route audio output and mic input through something (hardware or software) that would do noise cancellation on audio out you are hearing (ie avoid sending back thru microphone) - yes (but what is your budget, and how sophisticated are you with sound engineering? [old joking answer] if you have to ask, you probably can't afford it/are in wrong situation... )
Short version - you have to avoid audio loop. Your microphone can hear (usually) what your ears hear... and therein lies the problem to solve. If not already obvious to you, OBS is compositing sources, the audio is not running through OBS and then out, so OBS is not in the right position to noise cancel. A recommendation on what to use would depend on your specific circumstances... if you are prepared to spend real money, just use headphones ;^)
