Several parts combine into one character.

Compound ideograph: 門 (gate / door) on the outside + 耳 (ear) inside. Picture: someone leaning against a closed gate, ear pressed to the wood, listening to what's happening outside. The verb of "hearing" frozen into a domestic scene. Three forms: 繁體 聞 / 新字体 聞 / 简体 闻.

Watch out for a fascinating cross-language semantic split that learners must absorb: — Japanese: 聞 means almost exclusively "to hear / listen". The Japanese verb for "to smell" is 嗅ぐ (kagu, written with a different character). — Mandarin: 闻 has shifted in everyday use to mean "to smell". The Mandarin verb for "to hear" is 听 (tīng — a different character entirely). 闻 still means "to hear" in formal/written Chinese (闻名 = "famous", literally "having one's name heard"), but in spoken Chinese, 闻 will usually be interpreted as "smell/sniff": 闻闻这个 (wénwén zhège) = "smell this". This means the SAME character covers different sense-verbs in different languages — a classic CJK false friend trap.

Mandarin: wén, rising 2nd tone. 新闻 (xīnwén, news), 闻名 (wénmíng, famous), 听闻 (tīngwén, to hear about — formal). And smell-meanings: 闻一闻 (wén yī wén, to take a sniff).

Japanese: on-reading ブン (bun) for compounds — 新聞 (shinbun, newspaper — every Japanese household), 見聞 (kenbun, things seen and heard / experience), 風聞 (fūbun, hearsay / rumor). Less common モン (mon) in older compounds. Kun-readings: き.く (ki.ku) — to hear / listen / ask. The dual meaning "to hear" and "to ask" is essential — 聞いてもいい? = "Can I ask?", 音楽を聞く = "to listen to music", 雨の音を聞く = "to hear the sound of rain". き.こえる (ki.koeru, to be audible / to be heard).

Memory aid: an ear inside a closed gate — listening for what comes through.