What Is Bit Depth in Audio?
Bit depth determines how precisely each audio sample is measured. More bits means more precision, more dynamic range, and a lower noise floor. It is one of the three fundamental parameters of digital audio, alongside sample rate and channel count.
Bit Depth Explained
Each audio sample is a number representing the amplitude of the sound at that instant. Bit depth determines how many possible values that number can have. 16-bit: 65,536 possible values. 24-bit: 16,777,216 possible values. 32-bit float: approximately 4.3 billion possible values with enormous range. More values means the digital representation more closely approximates the original analog signal. The difference between adjacent values (quantization steps) gets smaller, reducing quantization noise.
Dynamic Range and Bit Depth
Each bit adds approximately 6 dB of dynamic range. 16-bit: 96 dB dynamic range. Sufficient for final distribution — CDs use 16-bit and cover the full range of human hearing. 24-bit: 144 dB dynamic range. Far exceeds human hearing capability (120 dB). Provides enormous headroom for recording and mixing. 32-bit float: Essentially unlimited dynamic range for practical purposes. The dynamic range advantage of 24-bit is the main reason professionals record at that depth.
Recording and Mixing Bit Depth
Record at 24-bit. Always. Modern audio interfaces support 24-bit natively. The extra headroom means you can record at conservative levels without worrying about noise floor. With 16-bit, recording too quietly means audible quantization noise. With 24-bit, you can record peaks at -20 dBFS and still have a pristine noise floor. Mix at 32-bit float internally — all modern DAWs do this by default. This prevents clipping within the mix bus during processing.
Dithering: 24-bit to 16-bit
When reducing bit depth for final delivery (24-bit master to 16-bit CD), dithering is essential. Dithering adds a tiny amount of noise that masks quantization artifacts. Without dithering, the transition from 24 to 16 bits can produce audible distortion on quiet passages. With dithering, the noise floor rises very slightly but the audio remains clean. Most mastering software applies dither automatically. Common dithering algorithms: TPDF, POW-r, and various noise-shaped options.
Choosing Bit Depth
Recording: 24-bit. No exception. Internal mixing: 32-bit float (automatic in modern DAWs). Final master: 24-bit for high-resolution distribution, 16-bit for CD. Distribution as MP3/AAC: Bit depth is irrelevant — lossy encoders handle it internally. Archival: 24-bit preserves all the detail from your recording session. There is no benefit to recording at 32-bit integer with consumer or prosumer audio interfaces — the electronics themselves do not achieve 32-bit precision.