Reflection, Diffraction and Resonance of Sound Waves (HSC SSCE Physics): Flashcards

Hard surfaces and sound

Reflect it

Soft surfaces and sound

Absorb it

Reverberation

Reflection arriving ≤0.1s, heard as prolonged sound

Reverberation distance threshold

≤17 m

Echo

Reflection arriving >0.1s, heard as separate sound

Echo distance threshold

17 m

Diffraction

Wave spreading through opening or around obstacle

Wave equation (speed, frequency, wavelength)

$v = f\lambda$

Speed of sound in air

$340 \text{ m} \cdot \text{s}^{-1}$

Why low-frequency sounds diffract more through doorways

Wavelengths (several m) comparable to doorway size (~1 m)