01_An introduction

Spatial audio is experiencing a surge of interest in the past few years. Due to faster computers, the accessibility of digital audio technologies, and the diffusion of VR, more and more artists, content creators, musicians, sound designers and engineers are turning their attention to immersive audio. Especially, Dolby Atmos and Ambisonics seem to share the lead in terms of diffusion, but while the first one is a patented technology primarily used in the film industry and the mainstream music sector, Ambisonics is an open source, free alternative that offers a wider range of applications and represents a common choice in the videogame industry [1], especially thanks to the possibility of easy decoding in binaural audio which, combined with head-tracking, makes it an optimal choice for VR and AR applications.

Ambisonics was first developed by Michael Gerzon in the 70’s at Oxford, but for a number of reasons it did not encounter great success from the beginning. It surely survived, but as a niche technology, employed a radical but restricted circle of composers, developers and researchers active in a handful of universities worldwide[3].  Hence the development of Ambisonics has not been very linear, multiple methodologies were developed parallelly at different institutions resulting in a wide range of often incompatible approaches and formats. This is now changing, thanks to the introduction of formats and methodologies that have set a standard in the workflow[4] and new user friendly and free tools available.

This change of scenery has made it clear for an increasing number of higher education institutions that Ambisonics could be the ideal spatial audio format for tuition, due to its versatility, the tools available, the compatibility with any different loudspeaker system, and its relative affordability (one needs as little as four loudspeakers to decode ambisonics and no additional licenses need to be purchased).  However, due to the open-source nature of Ambisonics and its relatively recent opening to the masses, instructors cannot yet rely on any formalized method for the teaching of this technology. In addition to that the information about this technology available online is often disorienting. In particular, we could outline three different types of information concerning ambisonics that we gathered in as many groups:

    1_ Tool specific material: All the instructions, tutorials and documentation provided for specific software or hardware tools, often giving a theoretical contextualisation of some type, but at a very arbitrary level and usually not objective in the description of alternative workflows.

    2_ Academic papers: The core of the knowledge about ambisonics. Extremely precious material, covering scientific aspects of the technology with the risk being too advanced for beginners and maybe not always practically useful for musicians and other regular users.

    3_ Independent divulgation: Mainly tutorials on YouTube, often on channels that cover sound production topics and see that Ambisonics is trending. Some can be useful, but the information provided is not subject to any fact-checking protocol and can therefore be imprecise or inexact.

We believe it is very important for students that want to access these technologies and master them at a high level that they are introduced to immersive audio with a methodology that provides enough theoretical knowledge to understand the functioning of spatial audio but that also shows potential practical applications, inspiring ideas and solving problems, to demonstrate the actual affordances of these technologies.

The School of Creative Media (SMC) at CityU, Hong Kong represents a very interesting context for testing such methodology. In fact, it offers a very wide range of subjects, including music and music technology, and different new media applications in contemporary arts and digital communication and the proposed method needs to be specific but also versatile. Having the opportunity to intercept many different projects, expectations and issues related to immersive audio, we are given the opportunity to design a toolkit that will be responding to the needs of many types of users, focusing on the most frequently encountered problems and providing all required information.

The OAT

The toolkit we have designed is aiming not only at providing the necessary theoretical information, but also to design, present and document software and hardware solution that would allow students to use Ambisonics in a various range of contexts that could go from presenting their installation in an art exhibition to simply monitor their work in their home studios.  We have therefore designed the toolkit as a modular set where the different elements are interconnected but also useful on their own. 

The three modules of this project are a hardware module in which we will describe possible solutions to build inexpensive loudspeaker setups for Ambisonics in a DIY fashion; a software module where we will be presenting the software tools available for Ambisonics work with a specific focus on free/open source software compatible with Linux and Raspberry Pi. All will be corroborated by a theory module explaining Ambisonics in details and providing documentation for the software and the hardware part.

To demonstrate the outcomes of the projects, we will track the results of the students involved in projects that use spatial audio and we will run perceptual tests over different loudspeaker setups to acquire practical evidence over the aspects of Ambisonics that are most relevant in the learning process.

References

[1] Horsburgh, Andrew J, Kenneth B McAlpine, and D Fraser Clark. "A Perspective on the Adoption of Ambisonics for Games." Paper presented at the Audio Engineering Society Conference: 41st International Conference: Audio for Games, 2011.

[2]  "'Into the Soundfield' - Michael Gerzon & Ambisonics at Oxford (Official Documentary 2018)." 2018, 'Into The Soundfield' - Michael Gerzon & Ambisonics at Oxford (Official Documentary 2018)

[3] Malham, David G. "The Early Years of Ambisonics at York." Paper presented at the Audio Engineering Society Conference: 2019 AES International Conference on Immersive and Interactive Audio, 2019.
In addition to the University of York we can include the Institute for Electronic Music and Acoustics – Graz; IRCAM – Paris; CNMAT – Berkeley, California; CCRMA – Stanford, California; DXARTS – Seattle, Washington; Virginia Tech - Blacksburg, Virginia.

[4] Nachbar, Christian, Franz Zotter, Etienne Deleflie, and Alois Sontacchi. "Ambix-a Suggested Ambisonics Format." Paper presented at the Ambisonics Symposium, Lexington, 2011.