5.5: Bit Depth (Resolution)

Bit Depth (Resolution)

Bit depth determines the number of possible amplitude values for each sample. It directly affects the dynamic range, which is the difference between the quietest and loudest sounds a medium can reproduce without distortion or noise. A higher bit depth increases resolution, lowers the noise floor, and provides more headroom.

Dynamic Range Examples (Approximate Values)

• Cassette tape: ~60 dB
• Vinyl record: ~70 dB
• 16-bit digital audio (CD quality): ~96 dB
• 24-bit digital audio (professional standard): ~144 dB

Each increase of 1 bit adds roughly 6 dB of dynamic range.

To determine the dynamic range of a digital signal, always multiply the bit depth by 6.

Bit Depth and Resolution

• 4-bit audio – 16 possible levels (~24 dB range)
• 8-bit audio – 256 possible levels (~48 dB range)
• 16-bit audio – 65,536 possible levels (~96 dB range)
• 24-bit audio – 16.7 million possible levels (~144 dB range)

Example of 4-bit audio (blue) superimposed over the (red) analog sound wave.