I think that the old method of creating a flute to specifically fit the body dimensions of the player had and has considerable practicality, especially for the beginner. In the long run, the flute that you are most comfortable with will be the one that you play the most. The flute that fits you is a sound description of both your spirit and your body. Response could be defined as the sensitivity of the flute to the air that you blow through it. In other words, response is related to how much wind effort is required to make the flute play a particular note.
Some flutes respond to very little air volume or air speed, while others require a great deal.
Some flutes have a response that is very similar through the entire range of the instrument, whereas other flutes are very sensitive in one range and very resistant in the opposite range. Flutes also vary greatly in back pressure,' or the resistance to the air moving through the flute. Back pressure is a measurable characteristic within the air column of the flute. Response is a description of how easily the flute plays, and is a highly subjective observation due to the fact that no two players blow in exactly the same manner. The response of a flute is frequently linked to its possible volume range.