"There is no word like "mmmmm""

"There is no word like "mmmmm"" When I was younger (I'm 27 now), when I block while speaking, my elder brother was keep saying "Stop. STOP! Speak slowly. Why are you keep saying 'mmmmm'? There isn't a thing sounds like 'mmmmm'." That was my blocking sound while trying to speak desperately. Coming from my laryngeal. These were one of the most heartbreaking moments of my life, all the time.