Wooden Kazoo Size Effects

Kazoo Project, 2021-08 by Steven Cooke

Instead of looking for a commercial Kazoo I decided to make one (and variations) from a pattern that I found on Instructables by CraftAndu https://www.instructables.com/Wooden-Kazoo/. Besides making just a basic kazoo, I wanted to experiment with the sizes to see what effect the body size and membrane area had on the sound produced.

Thin wooden slats, about 1/8" thick, 1" - 2" wide, 3" - 5" length. Wooden strips of about 3/16" square, as long as the body slats that you will use. Thinner widths may be too weak for use. They can be made with 1/4"-thick pieces, but the size is bulky for the amount of air volume. Standard wood glue. Small wood screws or cable ties long enough to go around the entire finished kazoo. Heavy waxed paper (other suggest heavy plastic bags or the 'window' in mailing envelopes).

The body parts were cut out of scrap pieces of mahogany that I had left from another project. The original design had a fancy-shaped rotating membrane holder. Getting the surfaces flat and parallel to hold the membrane properly was harder than it sounded. Also, the clamp shape reduced the available clamping area.

I used a table saw with a fence to cut the thin boards (left over from previous board trimming). A hacksaw with a fine blade was used to cut the shapes, followed by hand filing and sanding. A power drill with the shown bits and a 1-1/2" holesaw was used for the hole cutouts, and guide holes for the screws (to avoid cracking the thin wood with the screws). A hand screwdriver was used to tighten the screws. I did use a power sander to smooth and bevel the sides and edges before a final fine-grit hand sanding. The large kazoo membrane holder was attached using plastic cable ties and a tie-cutter/tensioner.

The first two sounding holes were drilled with wood borers - 16 & 20mm - and the final one was made with a 1-1/2” hole saw. CraftAndu recommended different sizes, but really, they should be the same diameter with sufficient width around the top part to seal the membrane well.

The body cavity size has no effect on the produced sound. The large and small versions with the same membrane size produced a similar tone and volume. The membrane size determines the volume of the sound, and only coincidentally needs a larger (width) body to accommodate it. The tone remains the same (the membrane is sympathetically/harmonically vibrating to whatever tone you are humming) but the volume increases quite a bit when going to the larger membrane from the smaller one.

The dimensions can be anything that you want. A larger body may need to have a reduced portion for the mouthpiece, and I found that a slight restriction of the airflow at the end of the larger bodies produces a better sound.

I glued the side pieces to the bottom piece first, and then glued the top piece onto them.

Following the original design, I made the fancier curved membrane holders. It is very important in all cases to get the flat surfaces parallel or the membrane (I used waxed paper) will not seal well. I did not have wingnuts to make an easily removable piece, so I just screwed the piece on.

I would just use a square piece on future versions because it doesn't look bad if you bevel the edges with sandpaper, and that will provide a better sealing surface as well.

The completed units shown here work well (see the video) and I will make the square membrane holder top before varnishing them for a finished instrument.

On my third variation with a larger membrane hole (1-1/2"). I went with just a square top piece held tight by cable ties. After gluing the parts together they were all tested using heavy waxed paper for the membrane.

Unless you really rip up the membranes, I don't think that frequent replacement will be necessary. Rather than screws of any kind, I used cable ties to clamp the membrane holder onto the body. The video shows how the different sizes affect the tone. As the sound is a sympathetic vibration of the membrane to your humming, the body size does not affect the tone, unlike other true wind instruments. However, due to the larger vibrating area, a louder sound will be produced by a larger the membrane.