These are called vocables, a form of non-lexical utterance - that is, wordlike sounds that arenāt strictly words, have flexible meaning depending on context, and reflect the speakers emotional reaction to the context rather than stating something specific. They also include uh-oh! (thatās not good!), uh-huh and mm-hmm (yes), uhn-uhn (no), huh? (what?), huh⦠(oh, I seeā¦), hmmn⦠(I wonder⦠/ maybeā¦), awww! (thatās cute!), aww⦠(darn itā¦), um? (excuse me; that doesnāt seem right?), ugh and guh (expressions of alarm, disgust, or sympathy toward somebody elseās displeasure or distress), etc.
Every natural human language has at least a few vocables in it, and filler words likeĀ āumā andĀ āermā are also part of this overall class of utterances. TechnicallyĀ āvocableā itself refers to a wider category of utterances, but these types of sounds are the ones most frequently being referred to, when the word is used.