I am playing a lot of classical music on soprano at the minute, and I'm finding the discipline required is very good practice. It really makes you concentrate on tone and dynamics etc. However I am finding the jump between C and D more of a problem than usual. Often on slow pieces, when the embouchure has to work harder, I find when I go from C to D or E, I am accidentally playing the altissimo note. What is going on here? Does anyone know any good exercises to cure the problem?