Yes, so many people sad it is normal.....but i heard a voice

hi , this is real , actually occur in my life...my personal experience. one day night i went to backyard of my house...and am peeing....suddenly i heard a voice which is mentioned my name....MANU MANU MANU.....i scared about that and i watched around anyone was there....but no one.....i continued my piss ...again calling MANU MANU MANU......i stopped and i rushed into house.....really i was scarred......after day i cross check that place....noting in there....i dont know the reason y it happened