Non-lexical backchannel

Non-lexical backchannel is a type of backchannel response. "A non-lexical backchannel is a vocalized sound that has little or no referential meaning but still verbalizes the listener's attention, and that frequently co-occurs with gestures. In English, sounds like uh-huh and hmm serve this role."

Example (1):

-Explainer: ["Do you know what we're gonna talk about today?", "It's called blockchain."]
-Explainee: ["What's blockchain?"]
-Explainer: ["That's a really good question.", "It's actually a way that we can trade.", 'Do you know what trade is?']
-Explainee: [Mmm-hmm, it's when you take turns doing something. It's when you give up most of what you want, right?] --> non-lexical backchannel

Example (2):

-Explainee: ["It's a large scale attempt to understand the wiring map", 'of the brain, essentially.']
-Explainer: ['Yeah, great.']
-Explainee: ["I think that it's definitely needed."]
-Explainer: [Huh.] --> non-lexical backchannel
-Explainee: ['Understanding the anatomy of the brain is definitely', "important but, it doesn't necessarily tell us everything", "about the function, there's some sort of temporal order", 'from neuron to neuron and region to region', 'that we may not be able to pick up.']