Bounce that Sound

Why it matters

Whisper into one dish at the science museum and your friend hears it thirty metres away at the other dish. Sound bounces with geometric precision — same rules as a mirror.

The idea in plain words

Reflection, but for pressure waves. Tap the terms.

∠i = ∠r (for sound too)

Why do empty rooms sound 'echoey' but furnished ones don't?

Same room, different absorption — concert halls are tuned exactly this way

• the mirror: hard surface — walls, cliffs, floors reflect sound well; soft, porous surfaces absorb it
• application: whispering gallery — curved walls keep re-aiming the sound along the surface to a far listener
• application: soundboard — stage shells reflect sound toward the audience instead of the ceiling
• Bare walls: hard, flat reflectors → strong reflections
• Curtains, sofas, people: absorbers → reflections die fast

Predict first

Sound reflecting off a hard wall obeys…

∠i = ∠r for sound too — that's how whispering galleries, band-shells and sonar all aim their echoes.

• the same laws as light: angle in = angle out, same plane — correct
• no fixed law — it spreads everywhere
• the opposite: it bounces back the way it came

What you do

Tilt the wall until the reflected sound lands exactly on the listener's ear.

Check yourself

Sound is a…

Particles just oscillate about fixed spots; the compression PATTERN travels. In vacuum: silence.

Best sound reflector among these:

Hard + smooth reflects; soft + porous traps and absorbs. Velvet and foam are what studios use to KILL echo.

A megaphone works by…

The horn's walls reflect the spreading wavefront back into a beam — pure geometry, no battery.

• longitudinal mechanical wave — it NEEDS a medium — correct
• transverse electromagnetic wave
• stream of air particles travelling to your ear
• A smooth concrete wall — correct
• A thick velvet curtain
• A foam panel
• multiple reflections that keep the sound energy directed forward — correct
• amplifying with electricity
• speeding the sound up