🔊 Speed of sound

Source speed: 100 m/s (360 km/h) Object preset: Custom value 🚗 Car — 30 m/s ✈ Fighter jet — 350 m/s 🔫 Bullet — 800 m/s 🛩 Concorde — 600 m/s

🌍 Medium

Medium: Air Helium — 965 m/s Water — 1481 m/s Steel — 5960 m/s

Air temperature: +20 °C

Speed of sound: 343 m/s

✈ Source

Flight altitude: 80 m Pitch of source: 440 Hz

🌐 Waves and Reflection

Fronts per second: 6 Style of wave fronts: Frame + semi-transparent Only frame Semi-transparent only Mach cone (when M > 1) Prandtl-Glauert singularity (when M ≈ 1) Observers Engine trail

🎥 Camera and time

Camera mode: Free orbit Follow source Side view Time slowdown: ×1.0

🆚 Compare with a second object

Compare with a second object

Speed of the other object: 200 m/s (720 km/h)

What does the simulation show?
The spheres are the sound's wave fronts. As the source moves, the waves ahead are compressed (higher pitch), and behind — stretched (lower pitch). This is the Doppler effect.

When M > 1, the fronts form a Mach cone — its shock is like a sonic boom 💥. Near M ≈ 1 around the aircraft, moisture condenses into a white 'skirt' called the Prandtl-Glauert singularity.

Flight Modes:
Subsonic (M < 0.95) — source is slower than sound, waves have time to spread evenly in all directions.
Transonic (M ≈ 1) — the source nearly catches up with its own waves; they "pile up" ahead — this is the sound barrier.
Supersonic (M > 1) — the source outruns sound; all fronts merge into a Mach cone behind it; the boom is heard only once the cone physically reaches the observer.

The Doppler effect in front and behind differs because the source 'catches up' with its previous waves (compressing them — higher pitch) and simultaneously 'runs away' from the following ones (stretching them — lower pitch): this is due to the source's motion relative to a stationary medium, not a property of sound itself.