if one makes a bracha on food and makes a noise that signifies something to others like uhuh… (meaning no! or stop it) is this a hefsek if one makes a noise betwen the bracha and the actually eating? Or does a hefsek only count if the one actually speaks a word, not just making a noise.
Lechatchilah (preferably), one should not make any noise at all.
However, bedieved, somebody who makes a noise such as “nu” or “uh-huh” and similar noises, will not have to make another berachah, and this is not considered as if he spoke an actual word.
See Shut Betzel Hachochmah 4:87, and sefer Birkas Habayis, Shaar 38, no. 2; the same ruling is quoted from Rav Elyashiv shlita in Vezos Haberachah, p. 16.