For any audio system, may it be, for example, an analogue electronic circuit, a digital circuit, a whole computer or a physical wave-guide, there will be some time lag between the instant at which the signal enters the system and the one at which the signal exits. This happens for a lot of reasons, from the finite propagation speed of sound waves to the AD/DA conversion times, from the time required by the operating system (if we are using a computer) to complete a task to even the eventual hysteresis of the system. Latency is very often considered an important parameter of audio systems, especially computers setups for audio purposes (that we refer as computer audio systems including any sound-card and operating system). More in depth, it is usually convened that latency should not be audible, that is, the user shouldn’t be able to hear any possible delay between its actions, which cause the input signal/event to be generated, and the relative sound output. However, this is not always the case.
But first of all, when latency is not audible?