gapjagi keun soriga nado neomu nollaji ma.

Literally, 큰 소리가 나다 is something like a big sound occurs or a loud sound comes out.

In natural English, it usually means:

• a loud noise happens
• there is a loud sound
• a loud noise is heard

Korean often uses 나다 with things like sounds, smells, and accidents to mean to occur / to come out / to be produced.

For example:

• 소리가 나다 = a sound happens / a sound is heard
• 냄새가 나다 = a smell comes out / something smells
• 문제가 나다 = a problem occurs

So in this sentence, 큰 소리가 나도 means even if a loud noise suddenly happens.

No. Here, 나도 is not the pronoun 나 meaning I / me plus 도.

It is:

• 나다 = to occur, to come out
• -아/어도 = even if / even though

So:

• 나다 → 나도

That means even if it happens or even if a sound occurs.

This is a very common point of confusion because 나도 can also mean me too in other sentences. Here, the grammar and context show that it is from the verb 나다.

-아/어도 means even if or even though.

So:

• 큰 소리가 나도 = even if a loud noise happens
• 비가 와도 = even if it rains
• 늦어도 = even if it is late

In this sentence, it sets up a situation that should not affect the listener's behavior:

• Even if a loud noise suddenly happens, don't get too startled.

So the structure is basically:

• X-아/어도 Y
  = Even if X, Y

Because 크다 is the dictionary form of the adjective to be big.
When a Korean adjective directly modifies a noun, it changes form.

So:

• 크다 = to be big
• 큰 = big / loud, when placed before a noun

Therefore:

• 큰 소리 = a loud sound

This is like using the adjective in an adnominal form.

More examples:

• 작다 → 작은 방 = a small room
• 예쁘다 → 예쁜 꽃 = a pretty flower
• 좋다 → 좋은 사람 = a good person

Here, 큰 소리 is more naturally understood as a loud sound/noise, not literally just a big sound.

In 큰 소리가 나다, 소리 is the thing that occurs or comes out, so it is marked with the subject particle 가.

• 소리가 나다 = a sound occurs / a sound is heard

With verbs like 나다, Korean often uses 이/가 for the thing that appears or happens.

Compare:

• 소리가 나요. = A sound is coming out / There is a sound.
• 냄새가 나요. = There is a smell.
• 문제가 났어요. = A problem occurred.

So 소리가 is very natural here.
Using 소리를 would suggest a different structure, usually with a verb that directly takes an object.

놀라지 마 is a negative command meaning don't be startled or don't get surprised.

It comes from:

• 놀라다 = to be surprised / startled
• -지 마 = don't ...

So:

• 놀라지 마 = don't be surprised / don't get startled

This pattern is very common:

• 가지 마 = don't go
• 먹지 마 = don't eat
• 걱정하지 마 = don't worry

This sentence is in casual speech, so 마 sounds informal and direct.

A more polite version would be:

• 놀라지 마세요.

Here, 너무 is best understood as too.

So:

• 너무 놀라지 마 = don't be too startled

In everyday Korean, 너무 can mean:

• too much / excessively
• and also very often very, especially in casual speech

But in this sentence, because it is followed by a negative command, it clearly means too much:

• Don't overreact with surprise
• Don't be too startled

So this is not just don't be surprised. It is softer and more realistic:

• being surprised a little is okay
• just don't be overly startled

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

In English, you usually need to say you in commands:

• Don't be too startled.

In Korean, the listener is understood from context, so you normally do not say 너는 unless you want special emphasis.

So this sentence naturally means:

• You, don't be too startled if a loud noise suddenly happens.

But Korean leaves that you unstated.

갑자기 means suddenly, and as an adverb it often has flexible placement.

In this sentence:

• 갑자기 큰 소리가 나도 너무 놀라지 마.

it modifies the event of the loud noise happening. Putting it near the front is very natural.

You could also see similar variations such as:

• 큰 소리가 갑자기 나도 너무 놀라지 마.

That still makes sense, though the original word order sounds smooth and natural.

So yes, adverbs like 갑자기 can move around somewhat, but the original placement is a very standard way to say it.

Because 큰 소리 often means a loud sound or a loud noise, and in English noise sounds more natural in many contexts like this.

• 소리 by itself = sound
• 큰 소리 = loud sound / loud noise

In a sentence like this, English often prefers noise because it suggests something sudden and startling:

• If there is a sudden loud noise, don't be too startled.

So the Korean still literally has sound, but noise is often the most natural translation.

A polite version would usually be:

• 갑자기 큰 소리가 나도 너무 놀라지 마세요.

The main change is:

• 놀라지 마 → 놀라지 마세요

That makes the sentence appropriate for speaking politely to someone.

You could also say:

• 갑자기 큰 소리가 나더라도 너무 놀라지 마세요.

That sounds a little more formal or written, but the meaning is similar.

So the original sentence is casual, while 놀라지 마세요 is the everyday polite version.