The flute produces sound when air is forced through tubes. The family of flutes, which is Asian in origin, includes the transverse flutes, whistle flutes and vessel flutes. Notes are played on a by fingering keys or holes that change the pattern of air moving through the tubes. The dimensions, both length and width, of the tube change the pitch of the flute. http://library.thinkquest.org/11315/flute.htm The flutist blows a rapid jet of air across the embouchure hole. The pressure inside the player's mouth is above atmospheric (typically 1 kPa: enough to support a 10 cm height difference in a water manometer). The work done to accelerate the air in this jet is the source of power input to the instrument. The player provides power continuously: in a useful analogy with electricity, it is like DC electrical power. Sound, however, requires an oscillating motion or air flow (like AC electricity). In the flute, the air jet, in cooperation with the resonances in the air in the instrument, produces an oscillating component of the flow. Once the air in the flute is vibrating, some of the energy is radiated as sound out of the end and any open holes. A much greater amount of energy is lost as a sort of friction (viscous loss) with the wall. In a sustained note, this energy is replaced by energy put in by the player. The column of air in the flute vibrates much more easily at some frequencies than at others (i.e. it resonates at certain frequencies). These resonances largely determine the playing frequency and thus the pitch, and the player in effect chooses the desired set of resonances by choosing a suitable combination of keys. In this essay, we look at these effects one by one. The air jet vibrates The jet of air from the player's lips travels across the embouchure-hole opening and strikes against the sharp further edge of the hole. If such a jet is disturbed, then a wave-like displacement travels along it and deflects it so that it may blow either into or out of the embouchure hole. The speed of this displacement wave on the jet is just about half the air-speed of the jet itself (which is typically in the range 20 to 60 metres per second, depending on the air pressure in the player's mouth). The origin of the disturbance of the jet is the sound vibration in the flute tube, which causes air to flow into and out of the embouchure hole. If the jet speed is carefully matched to the frequency of the note being played, then the jet will flow into and out of the embouchure hole at its further edge in just the right phase to reinforce the sound and cause the flute to produce a sustained note. To play a high note, the travel time of waves on the jet must be reduced to match the higher frequency, and this is done by increasing the blowing pressure (which increases the jet speed) and moving the lips forward to shorten the distance along the jet to the edge of the embouchure hole. These are the adjustments that you gradually learn to make automatically when playing the flute. Flutists are usually taught to reduce the lip aperture when playing high notes. http://www.phys.unsw.edu.au/jw/fluteacoustics.html

a wind instrument is a musical instrument that pruduces tone through vibrating air. The air vibrates when the music player blows into or over the mouth piece, which is usually a tube, the length of the tube affects the pitch of the vibration. Once the air is vibrating inside the instrument some of the energy is radiated as sound out of the end and any other holes. not that useful but ya no, it did my homework hahaa (Y)