Bass Clef Changed to Treble Clef in the Middle of the Music Sheet (Are The Clefs Notes in Same Octave?) [duplicate]

Question

Halo, it may be duplicate of other questions with the same titles. But I don't find answers I'm looking for in those...

I'm quite new to music sheet, but I can basically read notes already after some time...

There is one part that is confusing me: when the lower (bass) clef is changed to trebel clef in the middle of music sheet.

Aren't the upper and lower clefs supposed to be the same octave when both clefs applied as treble clef? Like illustrated below. Is it so?

Because from this music sheet https://musescore.com/user/30710562/scores/6138973
When I see the piano keyboard demonstration, I find that the f (and other) notes from each clef are not in the same octave.
So the lowest visible line on upper treble clef is e5, and the lowest visible line on lower treble clef is e4?
Is it always so by default? Or not? Or there is something I miss from reading that sheet?

Answer 1

You are correctly understanding how to read the clefs. What you've missed is the "8-------" above the treble staff, which means to play those notes one octave higher than written.

Ordinarily, the top line of the treble staff would be F5, but because of the ottava symbol, it becomes F6.

In the linked piece, you'll notice that measure 53 has the same symbol written below the bass staff. In that case it means to play the notes one octave lower than written.

(Image source)

When "8----" or "8va-----" is written above the notes, it means to play one octave higher than written. "8----" or "8va------" or "8vb-----" written below the notes means to play one octave lower than written.

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See also: What is the meaning of an 8 followed by dotted lines?