Sample Rate and Bit Depth

Sound in the real world is analogue: it travels as a smoothly changing wave. Computers store and process numbers, so analogue audio must be digitised before it can be saved or edited. Digitising means taking measurements of the wave at regular moments in time and storing each measurement as a number.

Sample rate

Sample rate is the number of times sound is sampled each second, measured in hertz (Hz). A sample rate of 48,000 Hz means 48,000 measurements are taken every second. A higher sample rate takes more measurements per second, so the digitised version follows the shape of the original wave more closely. This makes the sound more accurate and improves quality. Imagine recording a friend's drum kit: at a low sample rate, a very quick cymbal hit might fall between samples and be missed. At a higher sample rate, there are more chances to capture it.

Bit depth

Bit depth sets how many bits are kept for every single sample. This decides how many possible levels each sample can be stored at, so it determines the accuracy of each measurement. With 8-bit depth there are 256 levels; with 12-bit depth there are 4,096 levels. More levels mean each sample can be stored closer to its true height, which gives better sound quality, especially for quiet details.

Sample rate and bit depth are different properties: sample rate is how often you measure the wave, while bit depth is how precisely each measurement is recorded.