Bit depth (audio)
The number of bits used to represent each audio sample. 16-bit covers consumer use (CD quality); 24-bit is the studio standard, giving more dynamic range and quieter noise floor.
Bit depth determines the resolution of each sample's amplitude. 16-bit allows 65,536 discrete levels (~96 dB dynamic range); 24-bit allows 16.7 million levels (~144 dB).
What it matters for
- Recording headroom. Studios record at 24-bit so they can pull levels up in mixing without exposing quantization noise.
- Quiet listening. At very low volumes, 16-bit's noise floor can become audible. 24-bit pushes it well below the threshold of hearing.
- Dynamic music. Classical and acoustic recordings with very wide dynamic range benefit; compressed pop does not.
Versus sample rate
Bit depth (amplitude resolution) is distinct from sample rate (time resolution — 44.1 kHz, 96 kHz, 192 kHz). The two together determine "hi-res" status. Most "hi-res" certified gear handles 24-bit / 96 kHz or higher.
In comparisons
For most listening, 16-bit / 44.1 kHz (CD / Spotify) is indistinguishable from hi-res in blind tests. The clearer win is on the recording and mixing side, where 24-bit is genuinely useful.