Sound Extrusions: The Ambisonic Engine

Ambisonic

Ambisonic

Let’s explore the heart of spatial sound distribution! Before we go on through another interview in the next blog post (and this one will be focused on sound installations with Czech hardware wizard Milan Gustar), let’s have a close look at Ambisonic Engine, which can be run in MAX/MSP. Some of the inspiration in this article will be discussed in the following interview as well.

Ambisonic is a spatial audio representation system developed by Michael Gerzon in the late 70’s. It’s often used in experimental and electro-acoustic music and offers a creative alternative to cinematic surround distribution systems. One of its advantages is it uses only four channels for spacial sound representation (and includes the height dimension of the sound source). This is a big difference compared to regular surround systems 5.1 or 7.1, which are using 6 or 8 audio channel respectively (including the subwoofer submix channel).

Within the Ambisonic world itself, the most used format is called B-Format (.amb format), which is the so called first-order Ambisonic. The soundfield is encoded into four channels in the encode-decode Ambisonic section. The main difference from conventional 5.1 or any other surround setup is, that Ambisonic engine creates virtual sound sources moving in spherical space. This means you can change the number of speakers any time, because it all comes down to representation of sound in spherical space and not within defined sound channels itself as in surround setups.

Ambisonic monitor

Ambisonic monitor

Dedicated soundfiled microphones (SFM) have been around since 70’s. But don’t be mistaken, Ambisonic is also ready for creative use, not just for dealing with captured authentic soundfield recordings or cinematic sound only. And that’s the way I use Ambisonic in my Sound Extrusions project. Basically you can take mono signal sources and position them in space – anywhere! 🙂 The position can be set or dynamically controlled by your own code in MAX. Once you define the speaker positions, the sound sources can be placed where desired. The Institute for Computer Music and Sound Technology in Zurich offers MAX/MSP Ambisonic externals for download.

There’s also a great online SOS article You Are Surrounded explaining all the details of Ambisonic engine and its advantages over surround systems and why it didn’t make into commercial success at the time, when it originated.

Just to tease you for the next blog post, we will be discussing with Milan Gustar new DOLBY Atmos sound system under current development, which is also platform independent as the Ambisonic engine.

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