Learning Mission

Interactive Echo Simulator

Change the distance, air temperature, and reflecting surface to investigate how sound travels to a wall and returns.

The simulator opens silently. Keep your device volume low before playing the sound pulse.

Audio safety: The optional pulse is short and gain-limited, but actual loudness depends on your speakers or headphones. Begin with device volume low. Microphone and live-feedback features are intentionally not used.
20 m
1 m50 m100 m
20 C
-10 C15 C40 C

Reflecting surface

Listener / sourceBrick wallReflecting soundReflected sound20 m one way
Round trip40 m
Sound speed343 m/s
Return delay0.117 s
Distinct threshold17.2 m
Distinct echo likelyThe reflected pulse returns more than 0.1 seconds after the original.
delay = 2 x distance / speed

Compare reflecting surfaces

The travel time depends on distance and sound speed. The surface mainly changes how strong the reflection is.

Try these echo experiments

Find the threshold

At 20 C, move the wall near 17.2 m. Notice where the calculated return delay crosses 0.1 seconds.

Change temperature

Keep distance fixed and warm the air. Sound travels slightly faster, so the reflected pulse returns a little sooner.

Change only the surface

Switch from curtain to concrete. Reflection strength changes, but the delay remains the same.