The musical art form is often considered subjective. This isn't the case. The musical art from is dependent on the physical attributes of the material world. Preference of style, is subjective, but quality of performance is not.
Allow me to explain.
So let us examine the singular note, as a physical phenomenon and see what lessons we can learn about it's objective expression shall we.
This is what is commonly know as middle C. On an instrument that plays in concert pitch middle C has a frequency range of 261.626 HZ. This frequency is calculated from it's relationship to the note A, which is 440 HZ.
I'll be making a post later to explain more in-depth what frequencies are and the mathematics that goes into them.
Anyway, the objectivity of the performance of a whole note of C is then dependent upon three things.
How close the performer omits the frequency of 261.626hz
How accurately the performer holds the note for the denoted length.
How steadily the performer keeps the note held.
Let's say, for easier calculation sake, that this whole note is going to be played in 120 beats per minute. So one beat every half of a second.
If the performer plays the middle C at a steady 261.626 hz for two second(because a whole note in common time denotes four beats, and each beat is half a second) and it is steady, then we can say this is an objectively good performance.
This aspect of music is objective, you might not like someones style, but a good performance is a good performance, no matter what.