When I first travelled to Egypt in September of 2001, my violin teacher there told me that my intonation on the violin was terrible. Nowadays when I play, certain good friends of mine, two masterful vocalists in the hindustani style, tell me that they've never heard anyone with a better sense of intonation than mine.
What is the cause for this change?
let's start with the obvious: two major things are different between the two assessments. The first is the difference in time (between 2001 and now, early 2009, almost 8 years later), and the second is the difference in observer (the first was an Egyptian violin player living in Cairo, and the second are a couple of Indian singers living in New York City.
I'd like to save the second difference for later, and treat the first difference first.
Between 2001 and 2009 I practiced the violin for many hours. I practiced playing arabic pieces on the violin over and over again. I practiced singing some arabic songs. I learned arabic, and learned more arabic over time (I had not learned it as a child, and started to pick it up when I went to Egypt in 2001).
whatever it was that I did, I was different in some specific way in between the two times. perhaps none of what I (am saying I) did had any effect, but it is certain that I was different in some way. This begs the question: what is it that can make someone different from one time to another? And different in the sense of being better (more skilled (able to accomplish some specific task or set of tasks in a more efficient and/or more precise and/or more entertaining and/or more beautiful and/or more coherent way))?
The question of skill acquisition is the same question across all disciplines, fields, languages, human activities: how do actions and/or time change the (relative) skill or people?
Thus, in a sense, in attempting to answer, to fully answer, that question in any specific field can yield insights into how that answer might manifest in other fields. Therefore I will approach that question through the one area where I believe I can attest to definite growth, if I take at face value the different assessments of my violin playing in 2001 and 2009.