Doppler Effect Simulator
Move a sound source and an observer and hear how the pitch changes with speed.
Drag the source or the two observers. Raise the source speed past Mach 1 to make a shock wave.
About the Doppler Effect Simulator
Free Doppler effect simulator. Drag a moving sound source and observer, change source speed, and see wavefronts bunch up, the observed frequency, and a shock wave at supersonic speed. Built for physics, the doppler effect simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Move a sound source and an observer and hear how the pitch changes with speed. Use it to explore physics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Doppler Effect Simulator
- Use the controls to change Source speed, Sound frequency. The simulation reacts instantly.
- Pick an option such as Still, Car, Almost Mach 1, Supersonic jet to switch modes or load an example.
- Press "Hear observer A", "Pause" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Increase the source speed and watch the fronts bunch up ahead of it.
- Drag the observer in front of and behind the source.
- Push the speed above Mach 1 to make the cone.
- Compare the observed frequency with the formula.
Key ideas you can learn
- A source moving toward you squeezes the waves together, so you hear a higher pitch.
- Moving away stretches the waves, so the pitch is lower.
- At the speed of sound the wavefronts pile up into a shock wave (Mach cone).
Where this is used in the real world
The Doppler effect is used in police speed radar, weather radar, medical ultrasound and to measure the expansion of the universe.
Who is this simulation for?
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams. It works well for flipped classrooms because students can explore before the lesson.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is the Doppler effect?
The change in observed frequency when the source or the observer is moving. Approaching raises the pitch, receding lowers it.
What is a sonic boom?
When a source moves faster than sound, the wavefronts overlap into a cone-shaped shock wave. An observer hears a sudden, very loud boom when it passes.
Is the Doppler Effect Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Doppler Effect Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.