interjection
Casual interjection used to show mild surprise, hesitation, or thoughtful acknowledgment. The drawn-out vowel gives it a relaxed, colloquial feel.
「明日、引っ越すんだ。」「ほーん、そうなんだ。」
"I'm moving tomorrow." "Huh, is that so."
ほーん、それでどうなったの?
Hmm, so what happened then?