Latency: Myths and Facts. Part 2. Why echo perception is different?

In a previous post I have talked about how a lowlatency audio system could be defined relating to (very little) ear physiology and (a lot of) common sense. This may seem odd, as this is not a rigorous scientific approach, but since the human hearing system is mostly unknown it makes some sense: it is impossible to pretend to model it to a very deep degree. Then, a bit of common sense must be used. Among the conclusions in the linked post there was that a system should be defined as effectively lowlatency when the latency is smaller than 2 ms, while should be simple to tolerate a latency as big as around 7-10 ms in most situations. I made the example of playing an electric/acoustic guitar in a room to get there, with an amplifier but being able to hear the direct sound as well. However, the requirement I got for the latency is much harsher than the usually agreed 20 ms. But from where that 20 ms came from?

Latency: Myths And Facts. Part 1.

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?

Contents in preparation

Ok, so… this blog will be slowly filled with something. This something will be some brainstorming stuff from science/audio/music topics. However, I am planning to go off-topic if something is interesting for me. More in deep, I’d like to publish content about acoustics, electronics and open source, all linked to music. I also wish to publish reviews of Linux distros and software, focusing on the audio capabilities and workflow. I would like to cover also hidden non-Linux operative systems I found interesting, as well as hardware reviews. I am planning to post electronics tips and maybe tutorials… there is something in the back of my head… I just have to find time and inspiration!

Still testing stuff in the meanwhile… here the three dimensional wave equation… just to test the $\LaTeX$ interpreter…

$\nabla^{2}p=\frac{1}{c^{2}}\frac{\partial^{2}p}{\partial t^{2}}$