Bản nhạc dài đến nỗi tôi quên điệp khúc.

Bản nhạc means a piece of music, musical piece, or tune/composition. It focuses more on the music itself.

By contrast, bài hát usually means a song, especially one with lyrics.

So:

• bản nhạc = a piece of music / musical composition
• bài hát = a song

In many situations, learners will hear both, but bản nhạc can sound a bit more focused on the musical work itself, while bài hát is more common for everyday song.

Đến nỗi is a very common pattern meaning so ... that ... or to the point that ....

In this sentence:

• dài đến nỗi = so long that
• Bản nhạc dài đến nỗi tôi quên điệp khúc
  = The piece of music was so long that I forgot the chorus.

A useful pattern is:

• [adjective/verb] + đến nỗi + result

Examples:

• Mệt đến nỗi ngủ quên luôn. = So tired that I fell asleep.
• Đắt đến nỗi tôi không dám mua. = So expensive that I didn’t dare buy it.

Because dài is the adjective being intensified.

The structure is:

• bản nhạc = subject
• dài = adjective (long)
• đến nỗi = so ... that / to the point that
• tôi quên điệp khúc = result clause

So the sentence is built like this:

• Bản nhạc
  • dài
    • đến nỗi
      • tôi quên điệp khúc

This is normal Vietnamese word order. The adjective comes first, then the consequence marker đến nỗi.

Yes.

• quên = to forget
• điệp khúc = chorus / refrain

So tôi quên điệp khúc means I forgot the chorus.

In English, we often need the, but Vietnamese does not have articles like a, an, and the in the same way. So điệp khúc can mean the chorus if the context makes it clear.

Điệp khúc means the chorus or refrain of a song.

It refers to the repeated section. In many contexts, it is the best translation for chorus.

Related vocabulary:

• lời bài hát = song lyrics
• giai điệu = melody
• ca khúc / bài hát = song

So here, điệp khúc is the repeated part that the speaker forgot.

Vietnamese often leaves tense unmarked if the context is already clear.

So tôi quên điệp khúc can literally be understood as I forget / forgot the chorus, and English chooses the tense based on context.

In this sentence, English naturally uses past tense:

• The piece of music was so long that I forgot the chorus.

If you wanted to make the past more explicit in Vietnamese, you could say:

• Bản nhạc dài đến nỗi tôi đã quên điệp khúc.

But đã is not required here.

Here, bản is part of the noun expression bản nhạc. It is not just a random extra word.

Vietnamese often uses measure words or noun-forming elements, and bản appears in expressions for certain kinds of composed or written items, including music.

So you should learn bản nhạc as a set phrase meaning piece of music.

Some similar patterns:

• bản đồ = map
• văn bản = text/document

In this sentence, bản nhạc is best learned as one vocabulary unit.

Yes, very naturally.

For example:

• Bản nhạc dài quá nên tôi quên điệp khúc.

This also means something like:

• The piece of music was too long, so I forgot the chorus.

The difference is mostly in nuance:

• đến nỗi = emphasizes the result strongly, like so ... that ...
• quá ... nên ... = more like too ... so ...

Both are natural, but đến nỗi makes the cause-and-result relationship feel especially strong.

Yes, it is grammatical and understandable.

That said, whether it sounds fully natural depends on context. In everyday speech, some speakers might choose slightly different wording depending on what they mean:

• Bài hát dài đến nỗi tôi quên điệp khúc.
• Bản nhạc dài quá nên tôi quên mất điệp khúc.

Why?

• bài hát may sound more natural if you are clearly talking about a song with lyrics.
• quên mất can sound a bit more conversational than plain quên.

But the original sentence is still correct and understandable.

Both mean to forget, but quên mất often sounds a little more natural or emphatic in everyday speech.

Compare:

• Tôi quên điệp khúc. = I forgot the chorus.
• Tôi quên mất điệp khúc. = I totally forgot the chorus / I forgot the chorus (more conversational, slightly more emphatic)

So in casual speech, many speakers might prefer:

• Bản nhạc dài đến nỗi tôi quên mất điệp khúc.

But plain quên is completely correct.

Because Vietnamese does not use articles like English does.

English requires:

• a song
• the chorus

Vietnamese usually does not have direct equivalents of a/an/the. Instead, definiteness is understood from context.

So:

• điệp khúc can mean a chorus, the chorus, or just chorus, depending on the situation.

In this sentence, the meaning is clearly the chorus because people normally understand a specific chorus in the piece of music being discussed.