My sound has changed so much, but in a good way I think
I have been told for years, ever since I got my gold flute, that I have such a dark sound. I'll never forget the first lesson after I bought my new flute. It was with my college freshman year teacher who I didn't get along too well with. Her response was that "nobody in a professional orchestra plays a japanese flute" and that "silver projects better than gold". Basically, she was pissed that I didn't come home with a Brannen or a different Boston-brand flute. Of course, she was just trying to get me to quit, and those comments certainly made me feel crappy after an $11,000 purchase. Fortunately, she was only my teacher for one year.
Ever since, I came to believe that my "dark" sound produced from my gold, Japanese flute was the reason I wasn't perfect. I never let it STOP me, but anytime someone would make a comment about how I wasn't projecting well, or how the conductor wanted a brighter sound I immediately blamed it on my flute and overcompensated by just blowing harder and playing with a very heavy vibrato because lots of vibrato gives the illusion of being louder.
It never occurred to me that the problem might be ME. The flute industry makes such a big deal out of the brands people play and how some are better than others, and I admit to have been slightly sucked in. I thought about buying a new, silver, bright, buzzy headjoint when I was auditioning for grad schools, but I didn't want to make a several thousand dollar commitment on my own, so I figured I'd put it off until grad school when I had a teacher to help me choose.
The thing I never expected is this: My teacher never asked me what kind of flute I played, whether it was solid gold, nothing. He told me to change my tongue position. Although the primary purpose was to clean up my articulation, it was step 1 in completely changing my sound. All of a sudden everything was clear and projection wasn't an issue. The sound was still a little TOO centered though. It lacked the floaty quality. Then came step 2 - changing my hand position. Again, the purpose was to fix my right hand technique, but less pressure on the right hand led to less pressure on the chin which was the beginning of the floaty sound. The real key though, was mastering a more relaxed embouchure and playing with air in the cheeks. My sounds is pretty much perfect now, and I didn't do it with practicing boring long tones for hours upon hours. Don't get me wrong, long tones are great and they have a place in each flutist's practice time. However, I hate too much of a focus on them.
I learned that the problems I had with my sound were actually ME and not my instrument. It was a hell of a lot cheaper, that's for sure. It also makes me wonder exactly how much the whole headjoint/flute thing REALLY has to do with the sound. I mean, I definitely think that you need a good quality instrument to begin with, otherwise you're just fighting with yourself. The difference between a handmade professional model is lightyears different than a top-of-the-line factory processed model. However, once you already have the quality, I think it might be wrong that people are looking for a "quick fix" by buying a new flute or headjoint. Many of them just doesn't realize that problems might be attributed to different areas, like bad tongue or hand position.
In conclusion, I have recently learned that no, I do NOT have a dark sound anymore. In fact, it's on the bright side, with a lot of depth and color and overtones. I love my sound, I love my flute, and I can hardly believe how much I have changed until I listen to recordings of myself prior to my own changes. Finally, I'm confident about my sound. It also doesn't hurt that my teacher tells me that I sound a LOT like Julius Baker..... :-)

