Digital Audio
Jitter is the variation in timing accuracy of digital audio clock signals, causing small, unwanted fluctuations in when samples are processed or transmitted. Excessive jitter leads to distortion, reduced stereo imaging, and a loss of sonic detail in digital systems.
In digital audio, timing precision is critical because each sample must be converted and transmitted at exact intervals defined by a clock. Jitter refers to deviations from these ideal timing points — when samples occur slightly earlier or later than intended. Although the variations are typically measured in nanoseconds, they can significantly affect audio quality if left uncontrolled.
Jitter can arise from several sources, including unstable clock generators, poor cable quality, ground noise, or data interference. In systems where digital signals are transmitted over AES/EBU, S/PDIF, ADAT, or network connections, jitter may also be introduced by signal reflections or improper impedance matching.
The audible effects of jitter depend on where it occurs. In digital storage and transmission, small amounts are tolerable if data is correctly buffered and reclocked. However, in digital-to-analogue conversion, jitter directly affects the timing of the reconstructed waveform, producing subtle distortion and a perceived loss of focus, clarity, or stereo width.
Professional audio systems use precise word clock generators, phase-locked loops (PLLs), and reclocking circuits to minimise jitter. High-quality converters often specify jitter performance in picoseconds (trillionths of a second). A well-designed digital audio system maintains synchronisation and stability by distributing a clean, low-jitter master clock to all connected devices.
