Audio Latency
Definition
Audio Latency
Audio latency is the time delay between when a signal enters a system and when it exits, caused by analog-to-digital conversion, DSP processing, network transmission, and digital-to-analog conversion. Measured in milliseconds, latency affects live monitoring comfort (above 10 ms is perceptible), lip-sync alignment (above 40 ms is distracting), and speaker alignment accuracy. SonaVyx measures system latency using impulse response analysis.
How It Is Measured
System latency is measured by sending a test signal through the system under test and measuring the time delay between the reference signal and the received output using cross-correlation. SonaVyx impulse response measurement reveals the total system latency as the time offset of the direct sound peak from time zero. For digital systems, the round-trip latency can be measured using the loopback measurement mode.
Practical Example
A digital mixing console processes audio from microphone input to speaker output with 2.8 ms latency (A/D conversion: 1.0 ms, DSP processing: 0.8 ms, D/A conversion: 1.0 ms). SonaVyx loopback measurement confirms the total latency. Combined with a 10-meter speaker cable (0.03 ms negligible) and 15-meter acoustic propagation (43.7 ms), the total input-to-ear delay is 46.5 ms — acceptable for speech reinforcement but borderline for live music monitoring.
Perceptual Thresholds
Musicians can perceive monitoring latency above 5 to 10 ms, which interferes with timing and performance. Above 20 ms, monitoring becomes uncomfortable for most performers. For video playback, lip-sync tolerance is approximately 40 ms before the delay becomes distracting. PA system delay alignment accuracy should be within 1 ms for crossover regions and within 5 ms for delay fill timing.
Sources of Latency
A/D and D/A converters typically add 0.5 to 2 ms each. DSP processing adds latency proportional to the buffer size — a 256-sample buffer at 48 kHz adds 5.3 ms. Network audio protocols (Dante, AVB) add 0.5 to 5 ms depending on configuration. FIR EQ filters add latency equal to half the filter length. These delays accumulate through the signal chain.
Reducing Latency
Minimize latency by using smaller DSP buffer sizes (accepting higher CPU load), using direct monitoring where possible, choosing low-latency audio interfaces and protocols, and avoiding unnecessary FIR processing. For live performance, in-ear monitors fed from a low-latency mix bus reduce the perceived latency compared to speaker monitoring that adds acoustic propagation delay.
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