Learn Hardcore Japanese: watasi ha omosiroi hanasi wo kikimasita.

は is pronounced wa when used as the topic particle (so わたしは). を is pronounced o as the object particle. This is a standard spelling–pronunciation quirk in Japanese.

What does は do in this sentence? Is it the subject marker?

は marks the topic, roughly “as for me.” The grammatical subject of 聞きました is also “I,” but は is not the subject marker; が is. Using は sets “me” as the frame of reference without special emphasis.

Why is 話 followed by を?

を marks the direct object of a transitive verb. 話 (story/talk) is what was heard, and 聞く is transitive here, so 話を聞きました means “heard/listened to a story.” You cannot use が here with 聞く to mean the same thing.

Can I use に or から with 聞く to say who I heard it from?

Yes, but they do different jobs and usually do not replace を:

Source: Xから面白い話を聞きました = “I heard an interesting story from X.”
Person you asked/interviewed: Xに話を聞きました = “I asked X / I interviewed X.”
Asking about a topic: Xについて聞きました or with specific items, 道を聞く (“ask the way”).

Does 聞く also mean “to ask”?

Yes. When directed at a person, 聞く can mean “to ask/inquire”:

先生に道を聞きました = “I asked the teacher for directions.” Avoid 質問を聞く to mean “ask a question”; that means “to hear a question.” To ask a question, say 質問する/質問をする or use 尋ねる.

What’s the difference between 聞く and 聴く?

Both are read きく. 聞く is the default for “hear/listen” and also “ask.” 聴く emphasizes attentive listening (music, lectures): 音楽を聴く, 講演を聴く. Many people still use 聞く in all cases in everyday writing.

Why is it 聞きました and not 聞いました? How is it conjugated?

Dictionary form: 聞く. Polite stem: 聞き + ます → 聞きます. Polite past: 聞きました. Plain past: 聞いた (typical く-verb pattern: 書く→書いた, 歩く→歩いた, 聞く→聞いた).

What exactly does ました add? Is it “I heard” or “I have heard”?

ました is polite past. Japanese doesn’t distinguish simple vs. perfect; context decides. 聞きました can be “I heard” or “I’ve heard.” For “have ever heard,” use the experience form 聞いたことがある.

Can I omit 私?

Yes. Pronouns are often dropped when obvious. 面白い話を聞きました is natural in most contexts. Keep 私 if you need to contrast or clarify who did the hearing.

Can I use が instead of は (私が…)? What changes?

私が面白い話を聞きました puts focus on the doer: “It was I (not someone else) who heard an interesting story.” 私は… simply sets “me” as the topic without that exclusive emphasis. The object remains 話を.

Can I change the word order?

Yes, Japanese word order is flexible as long as particles stay attached:

面白い話を私は聞きました (emphasizes the object)
面白い話は聞きました (topicalizes “interesting stories,” often implying contrast like “at least I heard interesting stories”) The neutral order is the original sentence.

Why is there no particle after 面白い? Could I say 面白いの?

面白い is an i-adjective and directly modifies the noun: 面白い話 = “interesting story.” To say “a story that was interesting,” use a relative clause: 面白かった話. 面白いの turns it into “an interesting one” (pronoun), e.g., 面白いのを聞いた.

What does 話 mean here? Is it “story,” “talk,” or “conversation”?

話 is broad: story, account, news, someone’s talk. 面白い話 could be a funny anecdote, juicy news, or an engaging talk. For a formal lecture, use 講演; for a fictional tale, 物語. Adding お makes it polite: 面白いお話.

How would I say “I was told an interesting story”?

Positive/neutral: 面白い話をしてもらいました or 友だちに面白い話を聞かせてもらいました (“someone told me/let me hear an interesting story”).
Forced/negative nuance: 友だちに面白い話を聞かされました (“I was made to listen to an interesting story”).

How do I say I overheard it or that it was audible?

Use the intransitive 聞こえる or set phrases:

面白い話が聞こえてきました = “An interesting story could be heard/I overheard something interesting.”
面白い話を耳にしました = “I happened to hear/learn an interesting story.”

Is 面白い always appropriate? What if I want a more formal tone?

面白い is common and casual. In formal or academic contexts, use 興味深い: 興味深い話を聞きました (“I heard an intriguing/interesting talk”). For “funny,” you can also use おかしい depending on context.