In fact, the location of dents on the instrument can cause specific notes to play sharp especially if the dent is on the lead pipe. It is a good idea to have dents removed for the best intonation of brass instruments. Dirt and corrosion can cause intonation problems as well. Added dirt inside the tubing of an instrument can cause air restriction which will contribute to poor intonation. Valve port alignment is yet another consideration for proper brasswind intonation.
Misaligned valves can cause some notes to sound sharp, thin, or non-resonant.
Both piston and rotary type valves can be misaligned. Often times, students are unable to determine if poor intonation is caused by their playing or by these instrument shortcomings. Thus, it is important that music instructors inspect the instruments of students who are experiencing difficulty with intonation. Another consideration that often gets overlooked is that the use of mutes affects intonation of brasswinds. An important component that affects intonation of stringed instruments is the bridge.