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Urbanozoo – Street Art and Spatial Audio

This month the Incursions Sauvages (Wild Incursions) exhibition opened at the Musée de la Chasse et de la Nature (Museum of Hunting and Nature) in Paris. This exhibition, which runs from 11th April to 12th September 2022, includes the work of seven street artists whose visual works blur the line between nature and city, bringing animals right into the museum. These are worth seeing on their own but Incursions Sauvages has the added bonus of incorporating an immersive audio artwork!

I had the great opportunity to work with acoustician and sound artist Sébastien Jouan on the Ambisonic sound installation. Urbanozoo!, by Sébastien, was composed the piece to echo the images in two of the visual artworks (by war! and Jussie TwoSeven) with which it shares a space. Urbanozoo! uses urban and wild sounds to create a unique narrative in which the urban sonic environment is drowned under the sound of a stampede and the cries of animals.

My part in the project was to spatialise Sébastien’s composition, as well as to take care of the technical playback side. For the spatialisation, Sébastien and I worked together to place and balance the sounds so that they told the story of his composition and matched the visuals of the street art. The audio was mixed in first-order Ambisonics for playback over a square of loudspeaker. In addition to the artistic work, we had the technical challenge of ensuring that audio was wireless, since we could not run cables along the floor.

The final result stands on its own but the experience is heightened when listening in the museum, surrounded by the works of war! and JussieTwoSeven. If you are in Paris, I highly recommend that you visit the museum to hear Urbanozoo! for yourself.

You can read more about it on the museum’s website (in English and French).

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New Plugin: aXDeesser

Today I am happy to announce a new plugin: aXDeesser. As the name suggests, it is a de-esser made specifically to be used on Ambisonic signals. It is available in VST3 format (Windows and Mac), AAX (Windows and Mac) for Pro Tools | Ultimate, and AudioUnit (Mac).

As with the other plugins in the aX range, the aXDeesser is available in first-order, third-order and seventh-order variations. You can pick the one that fits your needs. The introductory price is 50% of the standard price. It costs 10€ for first-order, 20€ for third-order and 40€ for seventh-order (excluding VAT/sales tax).

You can also get the aXDeesser in the aXBundles. If you have bought any of the bundles in the past then you can head over to the downloads section of your account to get it for free! Just download the latest bundle and you will find the aXDeesser with your other plugins.

Why an Ambisonic De-esser?

Processing Ambisonic signals has to be done carefully to avoid changing or destroying the spatial properties of the sound field, so you need a de-esser that is designed with this in mind.

The aXDeesser also takes advantage of the spatial information provided by Ambisonics to allow you to focus on specific regions of your sound field in order to trigger the de-esser processing, giving you even more control over your processing. Effectively, you use the virtual microphone as a side-chain signal to activate the de-essing processing on the full signal.

Who needs an Ambisonic de-esser?

You can use the aXDeesser on any Ambisonics stream, but it is most useful if you are processing signals recorded with Ambisonic microphones. Anyone working on complete mixes where access to mono-encoded sources are no longer available will also find it useful.

If you have a recording made with a first-order microphone, such as the TetraMic or Sennheiser AMBEO VR mic, then the a1Deesser will fit your needs. The a3Deesser will allow you to de-ess recordings from the OctoMic or Zylia microphone. The a7Deesser is overkill for recordings made with an Ambisonic microphone, but can be used on full mixed scenes or if used creatively.

So, if you have a recording made with an Ambisonic microphone then the aXDeesser is the perfect tool for de-essing. You can tame excessive sibilance, at the same time preserving spatial fidelity.

How does it work?

The plugin has two modules – a virtual microphone and the main de-esser module. The virtual microphone captures a signal that is used to feed the de-esser’s detection algorithm. When the microphone signals activates the de-esser, the processing is applied to the whole sound field.

You can control the direction of the virtual microphone, along with the focus. The focus essentially controls how directive the microphone is, with the maximum directivity depending on the Ambisonic order of the signal received by the plugin. The incoming signal order is shown in the bottom left of the plugin GUI. A focus of 0% gives an omnidirectional microphone response. Focus of 100% gives a cardioid response for a first-order signal and the beam narrows as the input order gets higher. The meter on the left of the GUI shows the level of the virtual microphone signal.

The de-esser has all of the usual controls you would expect to find. You can set the frequency, the bandwidth, level, compression ratio and attack and release times. The meter on the right of the GUI shows the gain reduction being applied to the sibilance band.


Does all of that sound like something that could be useful to you? If so, head over to the shop by clicking below. By buying from this website you will be helping support independent development of spatial audio tools. Thanks for your support!

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5 Things You Should Know About Ambisonics

Ambisonics is a wonderful format for 3D sound/spatial audio for many reasons: it is flexible, interactive, future-proof, and realistic. Despite being around since the 1970s, it is still very new to a lot of people and, like every technique, it has a bit of a learning curve. Here are 5 things every beginner should know about Ambisonics before getting started.

1  – You can’t listen directly to Ambisonic signals

If you work with traditional surround formats (5.1, 7.1 etc.) then you’re used to sending the sound where you want it. Dialogue to come from the screen? Centre channel. Sound effects and ambiences? Rear channels. You get the drift. 

Ambisonics is totally different. You take your mono or stereo sound and pass it through an encoder, such as the aXPanner, and you get B-format signals out the other side. Unlike traditional surround, you cannot pass these signals directly to your speakers and listen to them. If you do, you’ll not get anything that sounds particularly spatialised.

Instead, you’ll need a decoder that takes into account your loudspeaker positions and converts your B-format signals to loudspeaker signals. Or you can convert it binaural 3D audio for headphone listening. The aXMonitor plugin will do this for you.

2 – Ambisonics gets better with order

As soon as you start reading about Ambisonics you will quickly come across phrases like first-order, third-order, higher order. But what exactly does this mean? Without going into the deep maths of it, the order is a measure of how much spatial detail is in your sound scene.

Zeroth-order is the same as an omni-directional recording – all of the sound is capture but none of the directional qualities. First-order adds in x, y and z directions so we can now move the sound around. Higher orders use more complex mathematical functions. This increases the spatial resolution so it’s easier to discriminate the directions of multiple source when you are listening. If you would like to read in this about more detail you can check out one of my earlier posts.

Essentially, the higher the order you are able to use, the better the spatial quality of your work will be. The trade-off is that higher order require more audio channels to carry the spatial information. This needs more CPU. At first-order we need 4 channels, third-order it’s 16 channels and seventh-order it’s 64 channels!

Personally, I will always work in seventh-order to keep my work future-proof so I can archive in the highest possible quality. It’s trivial to convert from seventh- to first-order by dropping some channels. However, going the other way requires you to change settings or plugins throughout your projects(s). Better to do it right the first time!

3 – The channel sequencing matters!

Your Ambisonic panner will output the signals in a specific sequence. The decoder that you use will expect them to arrive in a particular sequence. If these don’t match, the final rendering will not have the intended spatial qualities. It should be easy to work without this becoming a problem, yes?

Unfortunately, no. There are quite a few Ambisonics conventions floating around and if you are using tools from different manufacturers you need to be sure they are all working with the same sequencing format. Channel sequencing can cause headaches even for the most experienced Ambisonics users.

These different conventions have tended to arise from mathematical formulations or practical considerations during Ambisonics’ time in the wilderness. The two best known these days are FuMa (short for Furse-Malham) an AmbiX (short for Ambisonic eXchange). For first-order signals FuMa uses the channel sequence W-X-Y-Z, while AmbiX uses W-Y-Z-X. This really isn’t something you can neglect.

Thankfully, the industry seems to have largely settled on the AmbiX convention for most purposes. This means you’re less likely to run into any confusion, but it can still happen – some tools, like Sennheiser’s AMBEO microphone A-to-B plugin, give the choice of FuMa and AmbiX. Just make sure you set it to the format expect by your decoder. The aX Ambisonic plugins all use AmbiX format specifically to avoid the confusion of different formats.

4 – The level relationship matters, too

This one is related to the last point. Different conventions set the levels differently between different Ambisonic channels groups. For example, the omni W channel is 3 dB weaker in FuMa than AmbiX format, while their first-order  (x, y, and z) channels match in level (but, remember, not in sequencing!).

Generally, if you get your channel order correct, the level relationships will follow. You just have to careful that you do not change the level of one channel without doing exactly the same to all of the others. Doing so will mess with the spatial qualities of your sound scene. This also applies for frequency-dependent level changes, like EQ.

5 – Ambisonics is very sensitive to phase changes

If you’re processing your B-format Ambisonics then you had better be careful you’re using the right tools. Anything you do to one channel has to be repeated exactly on all the others because even a small phase change in only one channel can ruin the spatialisation of your work.

I’ve prepared a short audio demonstration of this with a sample of pink noise. The noise is panned to the left using first-order Ambisonics and rendered binaurally using the aXMonitor. Every two seconds it switches between a correct rendering and one in which one of the B-format channels is delayed by only 0.1 ms (4.41 samples). Hardly a massive delay! With stereo it would barely be audible. With Ambisonics, it completely ruins the spatial impression – listen as the noise goes from fully to the left to splitting into two spatial distinct sounds.

Listen with headphones!

The practical point to be made here is that plugins that change phase (or level) have to have been designed carefully. Using multi-mono plugins will apply processing individually to each B-format channel and almost certainly ruin the spatial quality of your audio. The SSA Plugins aXCompressor, aXGate and aXEqualiser give you dynamic range processing and EQ that you can apply to B-format signals and preserve the spatial integrity of your audio.

So here are 5 things you need to know about Ambisonics before you get started. If you have more questions about setting up an Ambisonic project, leave a comment or get in touch. I’m always happy to answer questions to help you down the road to spatial audio and 3D sound.

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New Plugin: aXMeter Ambisonic Meter

aXMeter Ambsionic meter with a third order input signal

It’s time for a new plugin – and it’s free!

The aXMeter is an Ambisonic meter plugin (VST, AAX, AU) that shows the RMS and peak levels for each of the Ambisonic channels up to seventh-order. It’s GUI size varies dynamically depending on the order of the signal it receives. For first- to third-order it shows all of the channels up to third-order. If the input is a higher order it expands to show the new channels.

Just like previous updates, this plugin exists because it was requested by users who thought it would improve their workflow. So, if there is some feature you’d like to see added or a plugin you think would be worth having, get in touch! The more requests a particular feature gets, the faster it gets made.

And the Summer Sale is continuing. There are discounts of 20% to 50% on all of the plugins in the shop. If you purchase something then you’ll be helping to support independent development of spatial audio tools.

If you want to download the free aXMeter head over here.

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aX Ambisonics AAX Release + Sale

There is plenty to get through in this post. There is some big news, so let’s get right to it!

AAX Release – aX Plugins in ProTools

A lot of people have asked for the aX Ambisonics Plugins to be available in AAX format so I’m very happy to release them. At this point they are as a public beta (you can download the demo versions to test on your system) but they have been stable for private beta testers.

Please note that the plugins run on the Ambisonic buses available in Pro Tools Ultimate (formerly HD). Unfortunately, you cannot use them with the standard version of Pro Tools at this point.

Also note that the seventh order a7 Plugins will run in Pro Tools but are limited to third order processing by Pro Tools bus structure. If you work exclusively with Pro Tools, and don’t need VST versions, then you can save money by picking up the a3 Plugins – you won’t benefit from the a7 versions.

Bundle Discounts

You can now buy the full set of 7 plugins in one click as a bundle for a discounted price of 30% less when compared to buying them all individually. You can get them from the online shop here.

Sale Pricing

Until 31st July 2018 there will be at least a 20% discount on all plugin prices. The aXPanner and aXMonitor will continue with the 50% discount. Check out the shop for more details.

Academic Discount

If you plan on using the plugins for academic or educational purposes then the you can get in touch for a discount code for substantial extra discounts.

New Activation System

In order to provide offline activation, and perhaps a subscription payment option, the plugin activation system has been changed. If you are an existing customer you will need to enter the new activation number to the plugins after installing the new updates. This should be available in your account. I will also email out all of the updated serial numbers to ensure everyone gets them. If they are not listed in your account or you need the update before I have a chance to email you, please get in touch

Bug fixes

All formats of the aX Plugins have had a number of improvements to stability and performance under the hood. This won’t change how you use them but should improve the overall experience.

Aside from these performance enhancements, a bug was fixed in the macOS version of the aXMonitor that stopped custom HRTFs loading after they had been processed.

Coming Soon…

I am working on a few new plugins that will be out in the next few months. Some will be simple (and free), while another is shaping up to be something really interesting. Check back here to keep up to date!

In the meantime, if you want to support further development you can purchase the existing plugins at the web shop. Thank you for your support.

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aXMonitor Update: Personalised Binaural with SOFA Support

The aXMonitor plugins are today updated to version 1.3.2. If you have already bought one of the aXMonitor plugins, you can download the update from your account.  You should remove any old versions of the plugin from your system to avoid any conflicts.

Today’s update is all about getting more flexibility and personalisation for binaural rendering of Ambisoinics. This is probably the most requested feature update for any of my plugins, so I am very happy to be able to announce the new feature:

  • Load an HRTF stored in a .SOFA file for custom binaural rendering.

This allows you to produce binaural rendering for up to seventh order Ambisonics with whatever HRTF you want, providing you with the flexibility you need to produce the highest quality spatial audio content possible.

If you aren’t sure why so many people want personal HRTF support, keep reading.

Advantages of Personalised Binaural

Binaural 3D audio can be vastly improved by listening with a personalised HRTF (head related transfer function). It’s the auditory equivalent of wearing someone else’s glasses vs wearing your own. Sure, you can see most of what is going on with someone else’s glass, but you lose detail and precision. Wear your own and everything comes into focus!

With that in mind, the aXMonitor plugins have been updated to allow you to load a custom HRTF that is stored in a .SOFA file. Now you can use your own individual HRTF (if you have it) or one that you know works well for you. Once an HRTF has been loaded it will be available across to all instances of the plugin in other projects.

What is a .SOFA file?

A .SOFA file contains a lot of information about a measured HRTF (though it can be used for other things as well). You can read more about them here.

Where to get custom HRTFs

You can find a curated list of .SOFA databases here. The best thing to do is to try a few of them until you find one that gives you an accurate perception of the sound source directions. Pay particular attention to the elevation and front-back confusions, since these are what personalised HRTFs help most with.

If you want an HRTF that fits your head/ears exactly then your options are bit more limited. Either you can find somewhere, usually an academic research institute, that has an anechoic chamber and the appropriate equipment. Then you put some microphones in your ears and sit still for 20-120 minutes (depending on their system). Once it’s done, you have your HRTF!

But if you don’t fancy going to all of that trouble, there are some options for getting a personalised HRTF more easily. A method by 3D Sound Labs requires only a small number of photographs and they claim good results. Finnish company IDA also offers a similar service.

Get the aXMonitor

So if you like the sound of customised binaural rendering then you can purchase the aXMonitor from my online shop. Doing so will help support independent development of tools for spatial audio.




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50% Discount on aXPanner and aXMonitor

Today I’m having April sale and putting a 50% discount on my Ambisonic panning and decoding plugins for Windows (VST) and MacOS (VST/AU): aXPanner and aXMonitor. This offer runs until the 30th April 2018.

The aXPanner converts mono and stereo signals to YouTube360 compatible AmbiX-format Ambisonics. The aXMonitor decodes these Ambisonic signals to two-channel stereo and binaural (3D audio over headphones) formats to allow easy monitoring. Together they form the essential signal chain for spatial audio and are a great way to get started with Ambisonics.

You can check out my short tutorial on getting started with a basic Ambisonics chain here.

The aXPanner and aXMonitor available for three levels of spatial resolution: first, third and seventh order Ambisonics. Higher orders increases the spatial fidelity of the sound scene.

This 50% discount can be combined with additional 20% bundle discounts for additional savings.

You can read more details about them in my web store :

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o1Panner Updates to a1Panner

The o1Panner is dead. Long live a1Panner!

My first plugin release was a free first order encoder called the o1Panner. Today it gets an update to version 1.0.1 and a new name. Here is a list of the updates:

  • name change from o1Panner to a1Panner to match the naming convention of the rest of the aX Ambisonic Plugins.
  • Unifies the colour scheme with the rest of the a1 Ambisonic Plugins.
  • Removes the JUCE splash screen on first open of the plugin during a session.
  • Now available as an AudioUnit on Mac.
  • 32 bit Windows version available.
  • Mac VST and AU are now Universal Binary.

So, no changes to the features, just added flexibility to where you can use it.

To get the update, go to your Account page and download from the download link available there.

And no changes to the price – it’s still free!

Download a1Panner

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aXMonitor Update: Google Resonance Audio HRTFs

Today the aXMonitor plugins get their first major update to version 1.2.2. There are two major updates and one minor updates. Let’s start with the major updates:

  • The HRTFs used for binaural 3D sound have been regenerated using Google’s own Resonance Audio toolkit for VR audio. These are the same HRTFs used by Google in YouTube 360. The code released by Google is only up to 5th order, but was actually quite simple to extend to 7th order.
  • A gain control has been added to boost or cut the overall level for convenience.

The minor update is a fix to make sure the plugin reports the correct latency to the host when using the Binaural or UHJ Super Stereo (FIR) methods.

Google have just open sourced their Resonance Audio SDK, including all sorts of tools for spatial audio rendering. This update to ensures that you can aXMonitor ensures that you can mix your content on HRTFs that will be widely used across the industry.

The aXMonitor is available in 3 versions, providing up to first, third and seventh order Ambisonics-to-binaural decoding.

So if you’d like to start mixing your VR/AR/MR audio content just head over to my store. With your support, I can continue to update the aX Ambisonics Plugins to bring you the tools you want and need.




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aXRotate Update to v1.2.0: Now With Head Tracking!

The aXRotate plugin receives an update today to version 1.2.0 and it’s a big one!  What’s more, it now comes as a (Universal Binary) AudioUnit format for Mac!

If you have already bought it, you can download the update from the download section of your Account page. If you haven’t, you can pick it up at my online shop!




Version 1.0.0 was a plain vanilla Ambisonics rotation with yaw, pitch and roll control. Version 1.2.0 adds two new features that massively increase its usefulness:

  • Get head tracking by connect an EDTracker module.
  • Increase the spaciousness of your static binaural mixes by adding micro oscillations to the sound scene.

Let’s go into both of these new features in a bit more detail.
Continue reading aXRotate Update to v1.2.0: Now With Head Tracking!