# Sounds waves in recorders and octaves

• Nathan Massey
In summary, the octave hole on the back of a recorder is smaller when you play the higher notes because you increase the thumb pressure.
Nathan Massey
Hello,

I've searched the internet for an answer to this question but cannot find it. Not a homework question, I'm just designing a recorder and don't understand this.

A recorder is a fipple flute, meaning that it generates standing sound waves by finger placement over holes that change the wavelength. However, on the back of a recorder there is a hole that you hold fully closed with your thumb to play the standard octave, (C4), when the player half covers this back hole, the octave increases to C5. In terms of sound waves, how does half covering this hole accomplish this? Is it changing the wavelength, or is it something to do with pressure?

-Nathan

Not sure exactly what you mean by "pressure" but I think it is changing the wavelength by creating a nodal point of the pressure wave. I would guess that the hole would be located pretty close to 2/3 the length of the recorder?

What happens when you fully open this hole? My guess it probably changes the note only a tone or semitone?

Nathan Massey said:
A recorder is a fipple flute, meaning that it generates standing sound waves by finger placement over holes that change the wavelength. However, on the back of a recorder there is a hole that you hold fully closed with your thumb to play the standard octave, (C4), when the player half covers this back hole, the octave increases to C5. In terms of sound waves, how does half covering this hole accomplish this? Is it changing the wavelength, or is it something to do with pressure?
I have played the recorder very much, but I do not know exactly. I can give some theory, though.

On all woodwinds, going from the base tone to the octave means "short-circuiting" the base tone. This is done by opening a hole at a specific point relative to the base tone. Having one octave hole for each tone is theoretically perfect, but in practice it is impossible to play. That conundrum is solved in different ways:
• In a saxophone, there are two octave holes. Each of them is a compromise for half the octave and a complicated mechanical linkage changes between them.
• In a recorder, you only have one octave hole (since no complex mechanics are available). Since you cannot change between several octave holes, your thumb regulates the octave by altering the size of the octave hole. If you think about it, you automatically increase the thumb pressure when you play the higher notes. This has the effect of making the octave hole smaller.

## 1. What are sound waves?

Sound waves are vibrations that travel through a medium, such as air or water, and can be detected by the human ear. They are created when an object vibrates, causing changes in air pressure that our ears interpret as sound.

## 2. How do sound waves work in recorders?

In recorders, sound waves are produced by blowing air into the instrument, which causes a column of air inside to vibrate. This vibration is amplified by the recorder's body and exits through the instrument's mouthpiece, creating the sound we hear.

## 3. What are octaves in sound waves?

Octaves refer to a musical interval that is twice the frequency of another note. When two notes are an octave apart, they have a 2:1 frequency ratio. For example, if one note has a frequency of 100 Hz, the note an octave above it would have a frequency of 200 Hz.

## 4. How are octaves related to sound waves in recorders?

In recorders, the fingering pattern used to produce different notes is based on the concept of octaves. By covering or uncovering specific holes on the instrument, the length of the vibrating air column is changed, producing different frequencies that correspond to different notes.

## 5. Can sound waves in recorders be manipulated to create different sounds?

Yes, sound waves in recorders can be manipulated in a few ways to create different sounds. Changing the amount of air blown into the instrument, altering the fingering pattern, or using different materials for the recorder's body can all affect the quality and tone of the sound produced.

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