Nhịp nhanh đến nỗi mọi người hát lạc nhịp.

In this sentence, nhịp means rhythm, beat, or tempo, depending on context.

Here, nhịp nhanh most naturally refers to the tempo/beat being fast. In music-related contexts, nhịp often has to do with keeping time.

A useful thing to notice is that nhịp appears twice:

• Nhịp nhanh = the tempo/beat is fast
• lạc nhịp = to be off the beat, out of sync, off-tempo

So the sentence repeats the same core musical idea in two different expressions.

Vietnamese often leaves out the verb to be when describing something with an adjective.

So:

• Nhịp nhanh literally looks like tempo fast
• but it naturally means the tempo is fast

This is very common in Vietnamese. Compare:

• Trời đẹp = The weather is nice
• Cô ấy cao = She is tall
• Nhịp nhanh = The tempo is fast

You do not need là here. In fact, using là before an adjective in this kind of sentence would usually sound unnatural.

Đến nỗi means something like to the point that, so... that, or to such an extent that.

It introduces a result or consequence.

So the pattern is:

• X đến nỗi Y
• X is so... that Y happens

In your sentence:

• Nhịp nhanh đến nỗi...
• The tempo was so fast that...

This structure is very useful in Vietnamese. For example:

• Mệt đến nỗi không đứng nổi = So tired that one cannot stand
• Đắt đến nỗi tôi không mua được = So expensive that I couldn’t buy it

Yes, mọi người literally means everyone or all people.

In this sentence, it refers to the group of people singing:

• mọi người hát lạc nhịp = everyone sang off-beat

A small nuance: mọi người is extremely common in everyday Vietnamese and often sounds very natural in both spoken and written language.

It can also mean everyone in a room or group, not necessarily every person in the world.

Lạc nhịp means to lose the beat, to be off-beat, out of rhythm, or out of sync.

Breakdown:

• lạc = lost, astray, off course
• nhịp = beat/rhythm

So literally it is something like to lose the rhythm/beat.

In music, it means someone is not following the timing correctly. More broadly, lạc nhịp can sometimes also be used figuratively for things that are out of step or not in sync.

Here, nhanh functions like an adjective describing nhịp.

• nhịp nhanh = a fast tempo / the tempo is fast

Vietnamese words are often flexible and do not always fit neatly into English grammar categories. Nhanh can act like fast/quick, and depending on the sentence, English may translate it as either an adjective or adverb.

For example:

• Anh ấy chạy nhanh = He runs fast
• Nhịp nhanh = The tempo is fast

So in this sentence, it is best understood as describing the noun nhịp.

Yes, that is completely normal.

The first nhịp is the thing being described:

• Nhịp nhanh = the beat/tempo is fast

The second nhịp is part of the fixed expression:

• lạc nhịp = off-beat / out of rhythm

So this is not awkward repetition in Vietnamese. In fact, it helps make the sentence more coherent because the result directly relates to the same musical idea introduced at the start.

English sometimes avoids repetition more than Vietnamese does, but Vietnamese often repeats key words very naturally.

Not exactly.

Lạc nhịp is about rhythm/timing, not pitch.

So:

• hát lạc nhịp = sing off-beat / sing out of rhythm
• hát sai tông or hát chênh/phô would be closer to sing out of tune

This is an important distinction:

• nhịp = beat, timing
• tông / cao độ / đúng nốt = pitch-related ideas

So if the problem is that people cannot keep up with the tempo, lạc nhịp is the right phrase.

Vietnamese often leaves time unstated if it is clear from context.

So mọi người hát lạc nhịp can mean:

• everyone sang off-beat
• everyone sings off-beat
• everyone was singing off-beat

The exact time depends on the situation or the translation provided.

If you want to make the past clearer, you could say:

• Nhịp nhanh đến nỗi mọi người đã hát lạc nhịp.

That is grammatical, but not always necessary. Vietnamese does not mark tense as consistently as English does.

It is most often used when the result feels extreme, noticeable, or somewhat undesirable, but it is not limited to negative situations.

In your sentence, the result is negative or problematic:

• the tempo is so fast that everyone loses the beat

That fits đến nỗi very naturally.

You can also use it in other strong-result situations, though it often still carries a sense of excess:

• Cô ấy xúc động đến nỗi bật khóc. = She was so moved that she burst into tears.
• Anh ấy vui đến nỗi không ngủ được. = He was so happy that he couldn’t sleep.

So the core idea is strong enough to cause a result, often an extreme one.

It could work in the right context, but it would be less clear on its own.

• Nhịp nhanh đến nỗi mọi người hát lạc nhịp clearly tells you that the tempo/beat is fast.
• Nhanh đến nỗi mọi người hát lạc nhịp just says so fast that everyone sang off-beat, but it does not explicitly say what is fast.

If the topic has already been established, Vietnamese can omit that noun. But as a standalone sentence, keeping nhịp makes it much clearer and more natural.