This setup can be used to measure the speed of sound by finding the tube length at which standing waves best form in the tube. This can be tested by measuring how much of the intensity of sound is lost when it has travelled through the tube. Reference the video for further explanation as to how this works.
Step 1: Tools and Materials
The setup requires the following components:
- Two tuning forks with the same natural frequency, with a resonance box like in the picture
- A PVC tube (~50cm)
- An at least 60x60cm piece of cardboard
- An at least 30x30x1.5cm (WxLxH) piece of plywood
- 4 screws
- PVC coupling pieces
You will need the following tools:
- A buzzsaw
- A stanley knife
- Measuring tape
- Duct tape
- A marker
- A drill
Step 2: Making a Tube of Variable Length
First, put marks at constant increments (of say 6cm) on the PVC tube. Then cut the longer tube into shorter pieces at these marks. These shorter pieces can be connected with PVC coupling pieces.
Step 3: Assembling the Box for Sound Shielding
First, cut the wood into 8 thin, long planks and one thicker plank. Use a drill to assemble these into 4 cornerpieces like in the first picture (predrilling may be required). Next, cut the cardboard into 6 rectangular pieces that are higher and wider than the tuning forks and their resonance boxes. Cut out a hole in two of these cardboard pieces at the same height as the openings of the sound boxes. Then, do the following twice: take two of the wood cornerpieces you just constructed and ducttape one of the cardboard pieces with the openings to them. Then, take two cardboard pieces that don't have a hole in them and ducttape them to the sides of the planks, creating a U-shaped wall. Reference the third picture for what this should look like.
The last thicker plank is meant to rest the PVC tube on so that it is at the same height as the openings in the cardboard boxes.