Let’s get right to it–learning how to properly tune your instrument, whether you are a beginner, an intermediate player or a professional–is one of the most important things to master early on as a flute player. It may seem like a complicated process, but it all boils down to this: the longer a tube is, the lower it will play, and vice versa. Learning to fine-tune (pun intended) this knowledge and applying it to your specific instrument will help you play in tune every time.
When you put your flute together, you should learn approximately where the headjoint needs to sit in the body of the instrument and make fine adjustments from there. The farther you draw the headjoint out, the longer the flute’s tube becomes and the flatter will become the pitch of your flute. The further you push in the headjoint the shorter the tube becomes and the sharper will become the pitch. The flute maker’s standard is that the headjoint should at all times be pulled out anywhere from three millimeters to as much as fifteen millimeters. The number of millimeters depends on the flutist’s individual embouchure, the design of their particular brand of flute, and on the temperature of the room that they’re playing in. If one day you were playing in an icy room with a VERY sharp piano, for example, you would need these extra millimeters for emergency sharpening.
Of course, any experienced flute player knows that intonation varies widely even when the headjoint is in perfect position. Some factors for this include headjoint cork placement, the scale of the instrument (modern flutes range from A=440 to A=443 or higher), and differences in breathing and dynamics. Even the most experienced players can get hung up on this. Blowing hard to play loudly causes the flute to go sharp. If you want to play loudly, don’t blow “hard”; blow with a focused and centered, penetrating core to the sound instead.