Cao độ của nốt nhạc khá cao.

Because the first cao is part of the fixed noun cao độ, which means pitch in a musical context. The second cao is the ordinary adjective high.

So the structure is:

• cao độ = pitch
• khá cao = quite high

It is not really repetitive in Vietnamese, even though English also ends up with pitch ... high.

Vietnamese often does not use a verb like to be before adjectives.

So:

• Cao độ của nốt nhạc khá cao = The pitch of the note is quite high

This is normal Vietnamese sentence structure:

• subject
  • adverb
    • adjective

You usually use là when identifying something as a noun, not when simply describing it with an adjective.

For example:

• Nó là giáo viên. = He/She is a teacher.
• Nó cao. = He/She is tall.

của shows possession or relationship, similar to of or 's in English.

So:

• cao độ của nốt nhạc = the pitch of the musical note
• literally: pitch of the note

It connects cao độ with nốt nhạc.

The subject is the whole noun phrase:

Cao độ của nốt nhạc

That entire phrase means the pitch of the musical note.

Then the predicate is:

khá cao = quite high

So the sentence is structured like this:

• Cao độ của nốt nhạc = subject
• khá cao = comment/predicate about the subject

khá means something like quite, rather, or fairly.

It suggests a noticeable degree, but not the strongest possible one.

A rough comparison:

• hơi cao = a little high
• khá cao = quite/fairly high
• rất cao = very high

So khá cao sounds moderate but clear: the pitch is definitely high, just not extremely high.

Because words like khá, rất, hơi, and quá usually come before the adjective they modify.

So:

• khá cao = quite high
• rất cao = very high
• hơi cao = a little high

You would not normally say cao khá here.

Vietnamese nouns usually do not have articles like a, an, or the, and they often do not show singular vs. plural by themselves.

So nốt nhạc can mean:

• a musical note
• the musical note
• sometimes musical notes, depending on context

In this sentence, it will usually be understood from context as the note or a specific note being discussed.

If you want to be more explicit, you can say:

• nốt nhạc này = this note
• một nốt nhạc = a note

In many contexts, nốt alone is enough to mean note.

But nốt nhạc is more explicit and clearer for learners, or in situations where you want to make it unmistakably musical.

So both can work, depending on context:

• Nốt này khá cao. = This note is quite high.
• Cao độ của nốt nhạc khá cao. = The pitch of the musical note is quite high.

It is grammatical and understandable, especially in a more technical or explanatory context.

But in everyday speech, Vietnamese speakers might often choose a simpler sentence, such as:

• Nốt nhạc này khá cao. = This note is quite high.

That sounds more direct and less formal.

Your original sentence is fine when you want to focus specifically on pitch as a concept.

Yes. cao độ can also mean something like elevation or altitude in other contexts.

But here, because of nốt nhạc, the meaning is clearly musical: pitch.

So context tells you which meaning is intended.

This is a very useful distinction.

• cao độ usually means pitch in music, or sometimes elevation/altitude in technical contexts
• độ cao usually means height or altitude

For a musical note, cao độ is the correct word for pitch.

So:

• cao độ của nốt nhạc = the pitch of the note
• độ cao của nốt nhạc would sound odd if you mean musical pitch

As a learner, it is better to keep của here.

• Cao độ của nốt nhạc khá cao = clear and standard

Without của, the phrase sounds less natural and less clearly structured in normal Vietnamese. In some compressed technical styles, nouns may sometimes be packed together more tightly, but that is not the safest pattern for learners.

So the best choice is:

Cao độ của nốt nhạc khá cao.

A rough pronunciation guide is:

cao độ của nốt nhạc khá cao
≈ cow doh koo-uh noht nyak kha cow

But the tones matter a lot. Word by word:

• cao — level tone
• độ — heavy/falling tone
• của — hỏi tone
• nốt — sắc tone
• nhạc — nặng tone
• khá — sắc tone
• cao — level tone

So one important learning point is that even though cao appears twice, it has the same pronunciation both times, while the surrounding words carry different tones.