I am looking for adjectives/adverbs that express the quality and the extent to which the melody of a musical performance adheres to the prescribed composition.
For example, A4 has a frequency of 440Hz. But if somebody is asked to play or sing A4, the actual performance may result in a note with a different frequency. The greater the difference between the prescribed and the actual frequency is, the more unpure the sound it is.
So what are the correspondent adjectives? Just pure and unpure?