![](https://help.apple.com/assets/6298DD6145D6312EEB72FDD2/6298DD6445D6312EEB72FDE2/en_US/ad7760802da9da7f585863d996533353.png)
Overview of B-format surround encoding in Impulse Response Utility
B-format is a special way of encoding spatial information. It represents three-dimensional space using four audio streams:
W: sound pressure
X: front-to-back
Y: left-to-right
Z: top-to-bottom
The illustration shows you how these four audio streams interact with each other to create a three-dimensional spatial image.
![Figure. Technical illustration of B-format surround streams.](https://help.apple.com/assets/6298DD6145D6312EEB72FDD2/6298DD6445D6312EEB72FDE2/en_US/d4849c134f3b862dc5526504fff7ecd9.png)
Space Designer can decode and convolve these four streams into reverbs in all supported surround formats. Space Designer provides a comprehensive library of B-format impulse responses that use all four streams (W, X, Y, and Z). With Impulse Response Utility, you can encode all supported surround impulse response formats in B-format.
See Advantages of B-format surround encoding in Impulse Response Utility and Microphones for B-format recording in Impulse Response Utility.
Download the guide:
Impulse Response Utility User Guide: Apple Books