Effects of Sound Waves (Cambridge (CIE) IGCSE Physics): Revision Note

Pitch & loudness

• Changes in frequency and amplitude affect the pitch and loudness of sound waves

• The frequency of a sound wave is related to its pitch

  • Sounds with a high pitch have a high frequency (or short wavelength)

  • Sounds with a low pitch have a low frequency (or long wavelength)

• The amplitude of a sound wave is related to its loudness

  • Sounds with a large amplitude have a greater loudness

  • Sounds with a small amplitude have a decreased loudness

Echoes

• Sound waves reflect off hard surfaces

  • The reflection of a sound wave is called an echo

• The distance to the surface where the echo reflects can be calculated using the equation:

$\mathrm{distance}=\frac{1}{2}\times \mathrm{speed}\times \mathrm{time}$

• Where:

  • distance = half the total distance travelled by the sound wave, measured in metres (m)

  • speed = speed of sound in air (opens in a new tab), measured in metres per second (330 – 350 m/s)

  • time = total time for sound wave to travel to the surface and back, measured in seconds (s)