Understanding PCM Audio: The Building Blocks of Digital Sound

Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications.

The Sampling Theorem

According to the Nyquist-Shannon sampling theorem, to accurately reconstruct a signal of a given bandwidth, the sampling frequency must be greater than twice the maximum frequency of the signal. This is why 44.1 kHz is the standard for CD audio—it captures frequencies up to 22.05 kHz, just above the human hearing limit.

Bit Depth and Dynamic Range

Bit depth determines the "resolution" of each sample. 16-bit audio provides 65,536 possible levels, while 24-bit audio provides over 16 million. Higher bit depth increases the dynamic range and decreases the noise floor.