ambisonics

Ambisonics is a full-sphere surround sound technique that captures, encodes, and re-creates a sound field around a listener. At its core, ambisonics represents the acoustic field using spherical harmonics, enabling independent control of direction and rotation during playback.

The sound field is encoded into B-format, typically four channels labeled W, X, Y, and Z. W is the omnidirectional component, while X, Y, and Z describe the three spatial axes (front–back, left–right, and up–down). In first-order ambisonics, four channels capture the field; higher orders add more channels for greater spatial resolution.

Recording often uses a dedicated microphone such as the Soundfield microphone, which captures B-format signals (or equivalent signals can be obtained in post-production). Decoding converts B-format to loudspeaker arrays or to binaural renderings for headphones. Decoders can produce a variety of playback formats and allow the sound field to be rotated to match the listener’s orientation.

Ambisonics offers a flexible framework: the same B-format can be rendered to different loudspeaker layouts, from simple four-channel setups to immersive multi-speaker arrays, or to headphones with virtualized sound localization. This adaptability makes it suitable for music, film, virtual reality, gaming, and archival applications.

Key features include full-sphere capture (including elevation), compatibility with multiple encoding and decoding standards, and the development of higher-order ambisonics to improve spatial accuracy. The field continues to evolve with open formats, software decoders, and hardware implementations, enabling experimentation and broader adoption.