Ambisonics and the ATK toolkit for Reaper for multichannel playback.

This page contains links to sources containing information about Ambisonics, the Ambisonics Toolkit, and several tutorials on how to use the plugins in conjunction with soft and hardware.

Ambisonics

Ambisonics is a full-sphere surround sound technique used for recording, mixing, and reproducing three-dimensional audio. Unlike traditional stereo or surround sound systems, which typically only cover a horizontal plane (like 5.1 or 7.1 setups), ambisonics captures sound from all directions: above, below, and around the listener.

Here’s how it works:

1. Sound Field Representation:
2. Recording Ambisonics:
3. Playback:
4. Applications:

In summary, ambisonics is an advanced sound format that enables full 3D audio immersion by capturing and reproducing sound from all directions, offering a much richer and spatially accurate audio experience compared to traditional surround sound methods.

 

Hardware setup

A typical ambisonics hardware setup includes:

  1. Ambisonic Microphone: A microphone with multiple capsules arranged in a tetrahedral or other pattern (e.g., Sennheiser AMBEO, Zoom H3-VR) to capture sound in all directions.

  2. Audio Interface: A multi-channel interface to record the signals from the microphone capsules, converting them into digital B-format signals.

  3. Computer with DAW: A digital audio workstation (DAW) with ambisonics plugins (e.g., IEM Plugin Suite, SPARTA) to process, encode, and decode the B-format audio for playback or mixing.

  4. Monitoring System: For playback, either a multi-speaker setup (for full 3D sound reproduction) or binaural headphones for VR/360 applications.

 

Speaker setup 

Here are a few common multi-speaker configurations used in ambisonics for 3D sound reproduction:

  1. Quadraphonic Setup (4 speakers): Four speakers are placed at the corners of a square or rectangle around the listener (two in front, two behind), offering a basic but immersive spatial sound experience, laying the groundwork for more complex surround systems.

  2. Cube Configuration (8 speakers): Speakers are placed at the corners of a cube, with four on the ground and four at elevated positions to cover all axes (left-right, front-back, up-down).

  3. Dodecahedron Configuration (12 speakers): Speakers arranged in a dodecahedron shape (12 equally spaced vertices) to capture more detailed directional sound.

  4. 3D Hemisphere (16+ speakers): Speakers are arranged in a half-sphere around the listener (above, in front, behind, and around) for immersive sound, often used in dome environments.

  5. Icosahedron Configuration (20 speakers): Evenly spaced speakers form a spherical shape for highly detailed spatial sound representation, often in higher-order ambisonics.

  6. Spherical Array (32+ speakers): A full 360° sphere of speakers, providing the most detailed and immersive sound experience for advanced higher-order ambisonics setups.

8 speaker setup configurations:

There are several different 8-speaker setups used for immersive audio experiences, especially in ambisonics, spatial audio, and surround sound configurations. Here are a few common types:

1. Cube Configuration (3D)
2. Octagonal Setup (2D)
3. 7.1 Surround Sound Configuration
4. Double Quadraphonic Setup (Vertical and Horizontal Planes)
5. Dual Layer Circle (Upper and Lower Rings)
6. Surround Sound with Height Speakers (5.1 + Height)
7. Horizontal Circle (Octagonal Layout)

 

Ambisonic toolkit

Via the following link you can find the download for the ATK toolkit for Reaper, and tutorials. There is a short explanation 

ATK separates the task of production work with Ambisonics into three distinct elements.

alt text
The Ambisonic Toolkit paradigmatic workflow.

 

 

Author
Capture or synthesise an Ambisonic soundfield.
Image
Spatially filter an Ambisonic soundfield.
Monitor
Playback or render an Ambisonic soundfield.

 

In its most simple form, Ambisonics can be regarded as splitting the panning law into two separate parts: encoding (Authoring) and decoding (Monitoring), where final panning (decoding) is deferred to an actual loudspeaker array at the time of audition. The ATK considers the Imaging (transforming) of a soundfield to be a critical step; this is where the artist shapes and processes the soundfield in a coherent way which isn’t easily available via the other models for working with spatial sound.

Many publicly distributed implementations of Ambisonics provide only encoding and decoding. While giving flexibility regarding final playback, failing to include transformers misses out the concept of imaging and fails to capitalise on the advantages of the sound-field sound-image paradigm intrinsic to Ambisonics.

What’s the difference?

The real power in working with Ambisonic over other multichannel surround sound techniques is that rather than being restricted to a sound-scene based paradigm (where the artist is presented with tools designed to build up a ‘sound scene’) Ambisonics supports a soundfield-kernel model. Here we construct a soundfield in the abstract, and can then shape it as desired. The result may be shaped into a ‘sound scene’, or perceived this way – but a soundfield-kernel approach gives much greater flexibility, and directly supports the realisation of more abstract outcomes. We regard this model as idiomatic for Ambisonics.

Along with powerful soundfield transforms – the spatial filtering tools enabling soundfield-kernel reshaping – the ATK provides a comprehensive set of Ambisonic encoders (including pseudo-inverse) and decoders (5.1binauralUHJ, full-3D) allowing users to thoroughly leverage the power of the Ambisonic technique.


Revision #2
Created 15 November 2023 10:52:40 by Tjerk
Updated 16 October 2024 13:12:09 by Tjerk