Finding simple wind instruments suitable to make with very young children is hard, but the balloon bassoon is perfect. Easy to make and satisfying to play, children love this instrument, not least because it’s loud! In my early childhood education music incursion programs this is always one of the most popular instruments.

Balloon bassoons are also inexpensive – about A$4 if you use PVC pressure pipe, much less if you use cardboard tube.  It sounds like a very cheap saxophone, and it only plays one note. Technically it’s more like a sax or clarinet than a bassoon, but hey! The name was to good to pass up!

How easy is it to make? I can make one from scratch in less than 3 minutes, including measuring and cutting the pipe. I use this instrument in my program to show children how easy and quick it is to make a musical instrument (I pre-cut the pipe, but that’s all).

Children from about 4 and up can make it themselves with some adult assistance – you will have to cut the hose for them, and they will need assistance and close supervision if they are going to saw the PVC pipe.

Children as young as 3 can play it, although most 3 year olds will need to have the instrument held for them.  4 year olds and up can hold it for themselves, but learning the right way to hold it takes practice.

The full instructions are below, but if you prefer a visual guide watch this video:

Materials you will need

• 1 metre of 40mm PVC pressure pipe, class 9 (or strong cardboard tube of about the same diameter – mailing tube or the tube that dress material comes on works well)
• gaffer or duct tape
• A 10cm length of garden hose
• 1 round balloon
• Two strong elastic bands (I use size 32)

Tools

• A pair of garden secateurs to cut the garden hose (or strong craft knife)
• A tenon saw to cut the pipe (or a hacksaw, but the tenon saw is better)
• Tape measure
• Pencil
• Scissors
• Medium sandpaper

***Ridiculously obvious safety note***: please be careful when using tools like saws, secateurs and craft knives, as personal injury is possible. (Phew, hopefully that will stop the law suits!)

Wait! Millimetres?!

All dimensions are given in metric units. If you come from a country that uses inches, you have my sympathy – the metric system is infinitely preferable! But here’s a metric to inch converter you can use.

The pipe I use is nominally 40mm diameter, but it’s actually 48.25mm outer diameter and 44.1mm internal diameter. If you don’t have this size pipe available in your country, choose pipe which is closest to 44.1mm internal diameter. Different diameters will affect the pitch somewhat, but I wouldn’t worry about it too much since the pitch of this instrument is only approximate anyway.

Procedure

1. Mark the PVC pipe to a length of 740mm with the pencil and tape measure.  (This will give a pitch of VERY approximately G, one and a half octaves below Middle C; you can make the pipe any length between ~150mm and 1.5 metre.  Shorter lengths give higher pitches and are easier for children to hold.)

2. Cut the pipe with the saw, holding the pipe firmly while sawing.  (Try to cut the pipe squarely, but a little angle won’t affect the playability or pitch.)

3. Smooth the end of the pipe with the sand paper (to remove any crumbs of PVC).

4. Place a strip of gaffer tape around one end of the PVC pipe.

5. Fold the tape inwards into the pipe (this stops the balloon popping).

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6. Take the balloon and cut the closed end of it off with the scissors (about 1cm).

7. Insert the 10cm length of hose into the mouth piece of the balloon and secure it with an elastic band.

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8. Twist the second elastic band over the gaffered end of the pipe (stretch and twist it so that it wraps around the pipe two or three times).

9. Stretch the open end of the balloon over the gaffered end of the pipe and secure it by rolling the elastic band up onto the balloon with your thumbs.

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TAA-DAA! Your Balloon Bassoon is ready to play.

Hold the instrument with one hand close to the top of the pipe.  Hold the hose with your other hand and put the hose end in your mouth.  Stretch the balloon away from you and very slightly downwards over the edge of the pipe by lifting the end of the pipe to just above mouth level. Blow hard!

The balloon will begin vibrating rapidly against the end of the pipe, producing a loud mournful honking reminiscent of a bassoon or saxophone.

The balloon will only last for an hour or two of playing, but putting a new one on only takes a few moments. If children are going to be sharing this instrument simply rinse the hose in detergent and water, then rinse the soap off in clean water.

Playing techniques

Try touching the balloon’s surface with one finger while playing a note.  By pressing down lightly on the balloon it is possible to raise the pitch by about one to three semitones. This effect is more pronounced with shorter instruments.

You can also bounce your finger lightly and rapidly on the top of the balloon for a tremolo effect. Or you can move the hand that is holding the pipe slightly forwards and backwards.  This changes the tension on the balloon and creates a pleasant vibrato as the pitch goes slightly up and down. Lifting the pipe slightly up and down gives a similar effect.

If you stretch the balloon out hard and then gradually bring your hand towards you, the note will drop in pitch as the balloon gets looser, by as much as a fifth or more.

But it only plays one note!

True, and because it’s such large diameter pipe, finger holes won’t work. It’s possible to cut a large hole, around 2.5cm diameter, about 1/3rd up from the bottom of the pipe, which you can cover with the palm of your hand, but that’s very difficult for young children to do.

So instead, why not make several balloon bassoons of different lengths?  If you make one that is 300mm long it will be approximately G, one octave higher than the 740mm version.  410mm gives approximately D.  Or just make them random lengths – instant wind band!

You can also make this using 90mm stormwater pipe and a giant balloon. If you make it around 1.5 to 2 metres long it sounds astonishingly like a digeridoo. It’s a lot harder to blow than the thinner pipe, so it’s most suitable for older children or adults.

How does it work?

The balloon acts as a reed, similar to the reed in a saxophone or a clarinet. The reed acts as a kind of gate: as you blow the pressure increases and the “gate” opens. This allows a pulse of air through the “gate” and the pressure drops, the gate closes, and so on, many times per second. For this length pipe that frequency of opening and closing is around 98 times per second.

The air coming through the pipe in pulses makes the column of air inside the pipe vibrate in sympathy with the pulses, and the frequency of the pulsing depends mainly on how long the pipe is. Longer pipes have deeper resonant frequencies (the frequency that the air “wants” to vibrate at), so they produce deeper notes.

But there are other factors to take into account. You will have noticed that throughout this post I have said that the pitch of these instruments is approximate. Very approximate: the pitch is greatly influenced by how tightly the balloon is stretched; the tighter the balloon, the higher the note. Also, balloons come in different thicknesses and a thin balloon will give higher notes than a thick one.

The internal diameter of the pipe also affects the pitch – larger diameter pipe will be slightly deeper than thinner diameter pipe.

This is a great instrument for demonstrating the physics of musical vibration with children. When children blow it they can clearly see the balloon vibrating as it opens and closes, and if they gently touch the surface of the balloon they can feel that it is vibrating.

If you have several instruments of different lengths the children can clearly see that on the shorter, higher-pitched instruments the balloon is vibrating much faster, and when they touch the balloon they can feel that it is vibrating much faster than for a long, lower-pitched instrument. It’s this difference in speed of vibration that results in different notes: the faster the vibration, the higher the note you will hear.

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This instrument is a greatly simplified version of an instrument invented by Bart Hopkin and you can see him playing his version at 2.20 of this video:

Bart is the doyen of weird and wonderful instruments and he has written some brilliant instrument making and design books which I reviewed here.

If you are interested in making more instruments I can’t recommend Bart’s books highly enough. Practically everything I know about musical instrument making I learned from Bart!