Learn Hardcore Korean: chaegeul sori naeeo ilgeoyo.

The particle 을 is the object marker. It tells you that 책 (“book”) is the direct object of the verb 읽어요 (“read”). If 책 ended in a vowel, you’d use 를 instead, but because 책 ends in a consonant, you use 을.

Why is there no explicit subject in 책을 소리 내어 읽어요?

Korean often omits the subject when it’s clear from context. Here, the speaker (I/you/we/they) is implied. In English you’d say “I read a book aloud,” but in Korean you can drop 저는 or 우리는 if you already know who’s doing the reading.

What does 소리 내어 mean, and why isn’t it just 소리?

소리 내다 is a verb phrase meaning “to make a sound.” When you attach -어 (the connective ending) to 내다, you get 내어, turning it into an adverbial modifier. So 소리 내어 literally means “making sound,” i.e. “out loud.” You can’t just say 소리 읽어요 because 소리 by itself is a noun (“sound”).

Could I say 소리를 내서 읽어요 instead of 소리 내어 읽어요? What’s the difference?

Yes, 소리를 내서 읽어요 is also correct. The ending -서 emphasizes “because of” or “by doing” the first action. So 소리를 내서 읽어요 feels like “I make a sound and then read.” 소리 내어 읽어요 is more neutral, simply linking “making sound” directly to “reading.” Both convey “read out loud,” but -어 is a bit more concise.

What tense and speech level is 읽어요?

읽어요 is the present tense polite (also called “informal polite”) form of 읽다 (“to read”). You use it in everyday conversation with people you’re not extremely close with: classmates, colleagues, or anyone where you want to be polite but not overly formal.

Is 소리 내어 읽어요 formal enough for a presentation or lecture?

It’s perfectly understandable, but if you want a more formal style, you could say 소리 내어 읽습니다. Switching 읽어요 to 읽습니다 raises the speech level to “formal polite,” which is common in public speeches, presentations, or news broadcasts.

Can you move 소리 내어 to the end of the sentence?

Yes, you could say 책을 읽어요, 소리 내어 in casual speech, but the most natural order is 책을 소리 내어 읽어요. Placing the adverbial phrase 소리 내어 right before the verb 읽어요 makes the sentence flow better and clearly links the manner to the action.

How would I say “read silently” instead of “out loud”?

You can use 조용히 or 소리 없이 before 읽어요:

책을 조용히 읽어요. (“Read the book quietly/silent.”)
책을 소리 없이 읽어요. (“Read the book without making any sound.”)