How Does A Flute Work?

The flute is the oldest known musical instrument used by our ancestors in far-off antiquity. The oldest example we have of a flute to date was made from the left thigh bone of a cave bear in Divje Babe Cave, near Cerkno, Slovenia. It was found with the remains of other stone-age tools and is believed to have been made 60 000 years ago by Neanderthals.

This flute is the only verified flute known to be made by Neanderthals and is 20 000 years older than other flutes made by anatomically modern humans. This pushes back our understanding of the history of music and proves how far back our desire to express ourselves musically goes.

Flutes have existed in many forms across the globe, and are a testament to the presence of developed musical tradition from the earliest period of modern humanity

What Is A Flute?

The flute is a family of woodwind instruments. Unlike woodwind instruments that use a reed, flutes are reedless and produce their sound from the passing of a flow of air across an opening. The earliest and most basic types of flutes are simply open tubes into which air is blown.

The most succinct answer, then is that a flute is a tube with holes.

Technically then, any instrument where air is blown through an opening can be classified as a flute. Flutes can be side-blown (traverse) like the orchestral flute, end-blown like pan-pipes, or use a fipple to channel air across an opening, as with a recorder.

This definition even qualifies a referee’s whistle as a flute.

On all these different flutes, they share one thing in common; a stream of air is passed through an opening and directed to a sharp edge at or near the opening, which causes the air stream to split, with some of the air entering the flute.

The quality of the sound produced will depend on several factors which we’ll look at shortly.

Brief History Of The Flute

Whilst the earliest discovered flutes to date have been found in Europe, this is not to say that this is their only place of origin. Flutes have been used by different cultures around the world stretching back to ancient times.

A 9000-year-old bone flute that is reportedly still playable has been excavated from a tomb in Jiahu, in the Central Chinese province of Henan. This flute was made from the wing bones of red-crowned cranes. The earliest Chinese transverse flute is known as the chi, discovered in the Suizhou site, Hubei Province China, in the tomb of Marquis Yi of Zheng. It dates from the Zhou Dynasty, 433 BC.

Flutes have long been an important part of Indian history and mythology, with the god Krishna routinely depicted as playing a transverse flute. Indeed, many believe the transverse flute originates in India.

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Different Types of Flute


The most basic type of flute is a simple tube into which air is blown. There are several different types of flute, but with most of them, the player blows directly over the mouthpiece, with about 1/4 of their lower lip covering the embouchure hole.

You blow air through a fipple on this recorder

However, some flutes have a duct, known as a fipple, to direct air onto the edge. These include, but are not limited to instruments such as the ocarina, flageolet, recorder, and tin whistle.


A further distinction can be made between transverse (side-blown) and end-blown flutes. Examples of transverse flutes include the western concert flute, the piccolo, the fife, the Indian bansuri, and the Chinese dizi.

A player of a traverse flute blows into a hole on the side of the tube to produce a tone, instead of blowing directly into either end.

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End Blown Flutes

End-blown flutes include the ney, shakuhachi, xiao, danso, and the quena.

End-blown flutes shouldn’t be confused with fipple-flutes such as the recorder, which are also played vertically. Fipples have an air duct to direct the airflow across the edge of the tone hole.

Open or Closed-ended?

Flutes can either be open or closed on either end. The pan pipes, police whistle, and ocarina are all examples of close-ended flutes.

This instructor is covering the end of this flute to make it closed-ended

Open-ended flutes include the western concert flute and the recorder. These types of instruments offer more harmonics and greater tonal variety and often have a brighter timbre

Resonator And Generator

All musical instruments have a few things in common; they all have a generator, the element that produces the vibration which we perceive as sound, and a resonator, something that amplifies the sound and creates the character of the specific instrument.

On a flute, the generator is the mouth hole edge, where the player directs their breath. The airstream rapidly fluctuates between going all into the hole, and away from it, and doesn’t split equally as may be expected.

What this does is start a rapid vibration at the head of the tube. The remainder of the flute tube functions as a resonator, or more accurately a container for the resonator, with the actual resonator being the air within the tube.

The mechanisms on the outside of a western, orchestral flute are for opening and closing the holes to adjust the pitch, and don’t have anything to do with the generation of the sound.

So How Is Sound Produced In A Flute

A jet of air is produced from the player’s lips and passes over the embouchure (lip opening) where it crashes against the sharp edge of the hole. If such a jet is further disturbed, then a displacement in the form of a wave travels along with it and either pushes it in or out of the embouchure hole.

The speed of the displacement wave on the jet is about half the speed of the jet itself (often 20-60 meters per second, depending on the pressure in the player’s mouth.)

The disturbance of the jet is the sound vibration in the tube (i.e. the flute) causing air to either flow into or out of the embouchure hole. If the jet speed is matched to the frequency of the note that’s being played, then the jet will flow in and out of the embouchure hole at its further edge. This will replicate the sound being played, causing a sustained note to sound.

The tube walls constrict air inside the flute, making it act like a stiff spring, independent of the air surrounding it. The moment when the air stream begins fluctuating in and out of the tube, this air spring receives a succession of little pushes, causing it to begin vibrating.

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It does not, however, vibrate at the same rate as at the mouthpiece. The vibrations at the mouth-end are strong enough to start the energetic chain of the air spring, but not strong enough to control the total rhythm of the vibrations.

The airstream uses the energy it receives to start vibrating at its natural rhythm. Its natural rhythm is determined by the length of the air spring. Once this vibration is initiated, the movement of air inside the tube becomes a chain of contractions and expansions.

Because the air spring is constricted, it holds on to some of the energy given to it and grows in strength. Soon, this overpowers the weaker fluctuations at the mouthpiece and makes the rhythm of these fluctuations vibrate at its rate.

Once this happens, the pushes given off by the mouth hole fluctuations will occur at the same time as each contraction of the air spring. The vibration builds to a point until it can vibrate the air around it, and a note is produced.

How Do You Change Pitch In A Flute?

To change the pitch of a note, a player can make slight adjustments to their lips and to the air pressure they expel.

To play a higher note, a player must increase the air pressure, which also increases the jet speed. This reduces the travel time of waves and matches with the higher frequency. The musician will also move their lips forward to shorten the distance between the jet and the embouchure hole. You can change the octave you’re in by using such techniques.

To change note, however, the length of the air spring must be changed. This is done by opening one of the holes on the side of the tube (i.e the flute.) Doing so removes the construction of the air at that point, effectively cutting the tube to the size of the new opening. Now the air spring only travels as far as this new point.

If a new hole is opened nearer to the mouthpiece, the air spring will end at that point. The vibrating portion of the tube will always be between at mouth hole and the first hole beneath it that’s open. This only applies, however, to the first octave playable of the particular note.

In the traditional flute, you can press down these valves which will lengthen the distance the air travels through the tube and ultimately lower the note.

The shorter the air spring, the higher the note produced will be, due to the faster natural rhythm of the spring. To ascend the first octave of a flute, then, a flautist will start from the bottom of the flute, opening one hole at a time, shortening the air spring each time a new hole is opened.

On a modern, western flute with all holes closed, an air spring will vibrate about 262 times a second. With all the holes open, the spring will vibrate (contract and expand) at about twice that rate.

Related Reading: How to measure sound frequency

Flutes Are Open-Ended

Whilst it’s obvious that a flute is open on one end, at first glance, it’s not so obvious that it’s open on both ends. If you look at someone playing the flute, you’ll notice that they leave a portion of the embouchure hole open to the atmosphere when she/he plays.

The natural vibrations that occur inside a flute are due to resonances. What standing waves or resonances are available inside the closed tube of a flute? To answer this we have to refer to sine waves and harmonics.

Sine Waves And Harmonics

As the tube of a flute is open at both ends, this means that the total pressure at both ends has to be approximately the same as atmospheric pressure. In other words, the variation in pressure due to the sound waves (the acoustic pressure) is zero. These points are what are known as pressure nodes.

Inside the tube, the pressure doesn’t need to equal atmospheric pressure. The first resonance, (the pressure anti-node) which is the maximum variation in pressure, actually occurs in the middle.


When the air is moving in the manner described, this is what’s known as its fundamental vibration. It’s also vibrating at the number of harmonic vibrations, which are further vibrational patterns for the air spring.

Let’s look at the first harmonic. With all the holes closed on a flute, the air spring acts as if it were divided into two. As we’ve already mentioned, just as the entire spring vibrates (the fundamental frequency, these halves expand and contract alternately, in opposite times to each other. When one is contracting the other is expanding.

As each section is half the size of the original air spring, they vibrate twice the rate of their fundamental vibration. The air inside the tube also vibrates at a second harmonic vibration, where the spring is divided into three, and so forth. How high this chain continues depends on the size and fingering configuration of the individual flute.

Different Breathing Methods

There are several ways in which musicians breathe to produce sound on a flute. These include diaphragmatic breathing. This is the most efficient way to breathe and thus minimizes the number of breaths a player has to take.

Circular breathing involves inhaling through the nose and exhaling through the mouth. The benefit of this is that you can produce a continuous sound.

To Conclude

The flute is the oldest instrument known to have been used by mankind. Once you’ve heard to haunting and evocative tones of the bansuri or a ney, it’s not hard to see why. There is something so simple and elemental in the sound of a flute, it’s no wonder they’ve captured the artistic and spiritual imagination of humankind for at least 600 centuries.

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