Fooling the Ear
A Survey of Sound Auralization Methods

Matt Montag
AmbisonicsHRTFDigital Waveguide MeshWave Field Synthesis


What Works

  • Captures complete soundfield with only 4 microphones
  • Flexible output; can be remapped to arbitrary loudspeaker configuration
  • Different mesh structures match performance to scenario

What Doesn't Work

  • First-order ambisonics can only recreate an accurate soundfield at a single, centered listener location

What is it?

Ambisonics is best described as a directional audio recording and reproduction technique that is capable of encoding sound periphery (a full sphere soundfield centered around a single listening point) in as few as 4 channels. It is based on the notion that the direction of a sound source in relation to a listener can be decomposed and faithfully represented by its orthogonal (X, Y, Z) components. The first-order Ambisonics B-Format uses four channels labeled W, X, Y, and Z. The W channel is a non-directional component measured with an omnidirectional microphone. The X, Y, and Z channels are directional components that correspond to three figure-eight microphones in a right-angle configuration.

High-order ambisonics (HOA) adds additional recording channels to achieve greater localization accuracy and higher flexibility for playback in large environments. HOA research also begins to converge with WFS (wave field synthesis) research, as both aim at physically reconstructing the soundfield. The difference lies in HOA's origins in ambisonics, where the goal is not to recreate the entire soundfield, but to recreate an accurate soundfield at exactly the listener's location.
A 4-channel cardioid ambisonic mic

What is it used for?

Ambisonics has seen limited application in consumer audio electronics as an alternative to other multichannel formats such as quadraphonics and 5.1 channel surround. High order ambisonics is currently being applied in acoustic holophony research.

Essential Articles selected from 1570 articles

  1. Surround sound psychoacoustics by Gerzon, M.A. (1974)
  2. 3-D sound spatialization using ambisonic techniques by Malham, D.G. and Myatt, A. (1995)
  3. Further investigations of high order ambisonics and wavefield synthesis for holophonic sound imaging by Daniel, J. and Nicol, R. and Moreau, S. (2003)

Matt Montag 2010