Monthly Archives: May 2013

New VST Plugin – Stereo Near Field Compensation

I’ve finished a new plugin! It’s very simple but was made in the spirit of experimentation.

User interface for stereo near field correction plugin

User interface for stereo near field correction plugin

If you read yesterday’s post then you can get an overview of what it does.

In short: it compensates for the proximity effect when sitting a short distance from your loudspeakers. This is fairly standard practice in Ambisonics and was proposed by Michael Gerzon (the godfather of Ambisonics) for stereo listening. It’s primarily useful when you’ve got phase differences in your signal between the two loudspeakers.

This is the first plugin I’ve done a 64bit version of so I hope it works. In fact, I was using this simple plugin simply as an excuse to try out a new way of doing the GUI and compiling a 64bit version.

It’s working fine on my Windows and Mac systems but if it doesn’t work on yours then let me know. I’ve tested it with Reaper (32/64bit on Mac & Windows) and SONAR X2 (64bit Windows).

It’s available in both 32 and 64bit versions for both Mac and Windows.

You can download all of the different version here.

I’d be very interesting in hearing back from people if they think it’s worth taking into account if it’s one of those things that’s fine in theory but can be safely ignored in practice.

If you’re finding use for my VST plugins and would like to donate to give me further incentive to keep working on them then it’d be warmly welcomed.

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Optimised Stereo II – Near Field Compensation

How far away from you are your loudspeakers – are they within a couple of metres of where you’re sitting? If you’re in a home/project studio then I’m going to assume that they are. They might even be as close as a metre from your listening position!

So what? Why does it matter how close they are? Well, you’ve heard of the proximity effect when you record with a microphone, yes? It’s the bass boost that you get as you move nearer and nearer to the microphone. Well if you’re sitting nearby the your loudspeakers then this can happen as well. And it’s not just the bass boost because there’s an associated phase difference that goes with it. This can cause some issues with where we localise the sound at low frequencies.

It was suggested by Michael Gerzon in his 1992 “Metatheory of Auditory Localisation” that this should be corrected. He states

“It might be argued that the effect on localization at such low frequencies is “unimportant”, but we believe this not to be so insofar as the more things that are made correct the better.”

With that in mind, and in the spirit of experimentation, I’ve made a very simple VST plugin that does this. I haven’t had a chance to listen to it in a decent room (mine is currently untreated, but not for long) so I don’t know how well it works. It’s definitely a subtle effect in from my preliminary listens.

Basically it’s a case of taking your stereo signal right before the output, splitting it into Sum (L+R) and Difference (L-R) channels and high-pass filtering the difference channel. These are then recombined back into L and R before being output via your loudspeakers.

I don’t know if Gerzon was right but this sort of near field compensation (NFC) is very common with Ambisonics so I thought it’d be worth giving it a go for stereo. I’ll be very interested to hear what other people think: important or pointless?

I’ll try have the VST up tomorrow. I just need to write up some brief documentation for it this evening.

DAFx13 – Maynooth

A short post today:

I’ve had a paper accepted to DAFx-13 in Maynooth, Ireland this September. I’ve a few reviews to make but it I’m looking forward to it! I still waiting to hear if it’s a poster or a presentation.

It presents the results of the listening experiment I did in February for Ambisonics. It’ll be nice to get back to a conference and hopefully engage in some interesting discussions!

I almost feel like a real academic!