Common microphone bleed situations include headphones near vocal mics and the sound of adjacent drums entering the mics intended for other drums in a drum kit. What is microphone bleed/spill? When close-miking any particular sound source, microphone bleed/spill refers to all extraneous noise other than the intended sound source. Still, it is often difficult to achieve due to microphone bleed/spill, extraneous and ambient noise, and other noise factors. Clean audio is nearly always strived for in any sound recording or reinforcement.