Sound is analogue data. Unlike a computer, which works with discrete binary values, sound waves in the real world are continuous. To store sound digitally, the computer needs to take measurements of the sound wave and convert them into binary. This process is called sampling. The sound wave is measured at regular intervals, and each measurement is given a binary value.
Sample rate
The sample rate is the number of samples taken each second. It is measured in Hertz (Hz). A higher sample rate means that more measurements are taken each second, giving a more accurate representation of the original sound. However, it also requires more storage space. For example, a recording sampled at 44,000 Hz takes approximately 44,000 measurements every second.
Bit depth
The bit depth (or sample resolution) is the number of bits used to store each sample. A higher bit depth allows a greater range of values to be recorded, making it possible to represent the amplitude of the sound more precisely. This generally produces a more accurate recording, but increases the amount of storage required.
For example, with 8 bits per sample: 2⁸ = 256 possible values
With 16 bits: 2¹⁶ = 65,536 possible values
File size
The size of an uncompressed sound file depends mainly on:
Sample rate, bit depth * duration
Increasing any of these increases the amount of data stored. For example, a recording with a higher sample rate and higher bit depth will generally have better quality but require more storage space.
Stereo sound has two channels, while mono sound has one, so a stereo recording requires approximately twice as much data as an otherwise identical mono recording.
Higher sample rate/bit depth→ better potential quality but larger file size.
Lower sample rate/bit depth→ worse potential quality but smaller file size.