Physics Theory : Sound Waves

Sound is created by vibrations (of objects) that cause the material medium (air) to be compressed and contracted into sound waves.

Vibration is defined as the to and fro motion of a vibrating particle about its mean position.

Frequency is defined as the number of vibrations produced by a vibrating body in one second.
The SI unit of frequency is Hertz (Hz).
Frequency = Vibrations / Time

Time Period is defined as the time in which a vibrating body produces one vibration.
Time Period = 1 / Frequency

Wavelength is defined as the distance between two consecutive crests (top points) of a wave is called wavelength. It is usually denoted by the Greek letter λ (lambda).

Velocity of a wave is defined as the product of the frequency and the wavelength.
Velocity of a wave = Frequency × Wavelength

Amplitude is defined as the maximum displacement of a vibrating body from its mean position.

Pitch is the effect produced in the ear due to the sound of a particular frequency.
Pitch is directly proportional to the frequency.
A high-pitched sound is very shrill, whereas a low-pitched sound is less shrill or softer.

Loudness is the characteristic feature of a sound that differentiates a loud sound from a feeble sound of the same frequency.
Loudness is directly proportional to the amplitude.

Sounds differ due to differences in their pitch and loudness.

Physics Quiz on Sound Waves.