[mathw]

Yes, there are.

And yes, it could sound different enough. If I invert the octaves of every alternate note it's going to be quite hard to pick out the melody as being the same, because I'd have disrupted all the scales and arpeggios that are the parts we actually recognise as forming the shape of it.

The other point the comment you're replying to is trying to make is that Western music generally has 12 tones per octave (even if they don't use them all, a lot of music uses 9 or 10 of them), and other musical systems used in various parts of the world in antiquity and in the present day may have significantly more (or less).

Anybody who limits it to 8-tone octaves and only a one-octave span and says it's every possible melody is just lying or musically ignorant. Which is surprising given who the people who did this claim to be - i.e. they're musicians.

It's likely that the article's author massively exaggerated on the "every possible melody" thing, because there are way more than you can get from 8 tones in 1 octave over 12 beats.