USB (Universal Serial Bus) Audio:

For many applications, the speed of digital communication is important. Most visibly, “speed” is about transferring large files as quickly as possible, or carrying enough data for an HD video. For USB audio (and for HDMI audio), “speed” is critical not because of how-much how-fast, but because time relationships within a digital stream are critical to the reconstruction of the analog wave form that brings information, music and joy to our ears. Time-based damage (jitter) to this information within the data package makes the sound small and flat instead of 3D, harsh and foggy instead of smooth and clear.