Physics - Sound: Vibrations and Pitch

Sound is a form of energy produced by vibrating objects. These vibrations travel through a medium (solid, liquid, or gas) as longitudinal waves.

The pitch of a sound refers to how 'high' or 'low' it sounds to the ear. It is directly determined by the frequency of the vibration.

Frequency ($f$) is the number of complete vibrations or oscillations per second. It is measured in Hertz ($Hz$).

A high-frequency vibration produces a high-pitched sound (e.g., a whistle), while a low-frequency vibration produces a low-pitched sound (e.g., a bass drum).

The time period ($T$) is the time taken for one complete vibration. It is the inverse of frequency: $T = \frac{1}{f}$.

Amplitude is the maximum displacement of a particle from its rest position. While frequency determines pitch, amplitude determines the loudness of the sound.

The human hearing range is typically between $20\ Hz$ and $20,000\ Hz$ (or $20\ kHz$). Sounds with frequencies above this range are called ultrasound.