balseongeul yeonseuphaeseo daesareul keuge malhaesseo.

발성 means voice production, vocalization, or how you use/project your voice. It is often used in contexts like:

• singing
• acting
• speech training
• pronunciation/voice exercises

So 발성을 연습하다 means to practice vocalization / voice production. In natural English, this might be expressed as to practice voice projection, to do vocal exercises, or to practice speaking with proper voice technique, depending on context.

발성을 uses the object marker -을/를, because 발성 is the thing being practiced.

• 발성 = vocalization
• 발성을 = vocalization + object marker
• 연습하다 = to practice

So:

• 발성을 연습하다 = to practice vocalization

You may also see 발성 연습 as a noun phrase meaning vocal practice or voice practice, as in:

• 발성 연습을 했어 = I did vocal practice

Both patterns are possible, but in your sentence the verb is directly 연습하다, so 발성을 is the object.

-해서 can connect two actions in a few related ways. In this sentence, it most likely gives either:

1. sequence:
   I practiced vocalization and then said the lines loudly

2. reason/result:
   Because I practiced vocalization, I said the lines loudly

Korean often leaves that distinction a little open, and the context decides which is stronger. Here, both ideas fit well:

• first I did voice practice
• as a result, I was able to say the lines loudly

So 연습해서 can feel like after practicing and also because I practiced.

Yes, but the nuance changes.

• 발성을 연습해서 대사를 크게 말했어
  = I practiced vocalization, so/and then I said the lines loudly

• 발성을 연습하고 대사를 크게 말했어
  = I practiced vocalization and said the lines loudly

-고 is a more neutral and, mainly linking actions in sequence.
-해서 often suggests a closer connection, such as because of that or as a result.

So if you want to emphasize that the vocal practice helped with speaking the lines loudly, -해서 is a very good choice.

대사 means lines or dialogue, especially in a script, play, drama, movie, or performance.

Examples:

• 대사를 외우다 = to memorize lines
• 대사를 말하다 = to say one’s lines
• 대사가 많다 = to have a lot of lines

So this sentence sounds like something from an acting or performance context more than ordinary conversation.

Because 크게 is the adverb form, and it modifies the verb 말했어.

• 크다 = to be big
• 크게 = bigly → in natural English, loudly or in a big way
• 큰 = big, as an adjective before a noun

Here, the speaker is describing how they spoke:

• 크게 말하다 = to speak loudly

You use 크게 because it modifies the action 말하다.

Compare:

• 큰 소리로 말했어 = I spoke in a loud voice
• 크게 말했어 = I spoke loudly

Both are natural.

Yes. Literally, 크게 comes from 크다, which means big, but with sound or voice it commonly means loudly.

So:

• 작게 말하다 = to speak quietly
• 크게 말하다 = to speak loudly

Even though the base adjective means big, in this kind of sentence the natural English meaning is definitely loudly, not bigly or greatly.

말했어 means said or spoke. With 대사, this means said the lines.

That works well if the person is:

• reciting lines
• performing lines
• speaking lines from memory
• practicing delivery

If you used 읽었어, it would mean read the lines, which suggests reading from a script or text.

So:

• 대사를 말했어 = I said the lines
• 대사를 읽었어 = I read the lines

Your sentence emphasizes speaking/delivery, not just reading.

말했어 is:

• past tense
• informal/casual speech

It comes from 말하다:

• dictionary form: 말하다
• past informal polite: 말했어요
• past informal casual: 말했어

So the whole sentence is casual, something you might say to a friend or someone close in age/status.

A more polite version would be:

• 발성을 연습해서 대사를 크게 말했어요.

The subject is omitted, which is very normal in Korean.

From the verb ending and the overall sentence, the implied subject is usually:

• I practiced vocalization and said the lines loudly

But depending on context, it could also be he/she. Korean often leaves out pronouns when they are already understood.

So without context, the sentence is literally more like:

• [Someone] practiced vocalization and said the lines loudly.

In real use, listeners usually know who is being talked about.

Yes, it is natural, especially in a context like acting, singing, speech training, or performance practice.

It sounds like:

• someone did vocal exercises
• then delivered their lines loudly / with stronger projection

One small nuance: in English, said the lines loudly may sound a little plain, but in Korean this is perfectly normal. Depending on context, 크게 말했어 could also imply projected the lines well.

So it is a natural sentence, especially if someone is talking about practicing for a performance.

Yes, absolutely. That is one of the most natural interpretations.

Because of -해서, the sentence can suggest a connection like:

• I practiced vocalization, so I spoke the lines loudly
• After practicing vocalization, I was able to project my lines loudly

Korean does not always spell out was able to, but the cause-and-result feeling can still be there.

So if the meaning shown to the learner was something like I practiced voice projection and said my lines loudly, that fits very well.