Recording for Surround Sound
What is the end goal? - stereophonic: concerned only with horizontal reproduction 5.1, 7.1, 10.2, most cinema sound - immersive: concerned with complete reproduction of soundfield (including height) Binaural, VR, gaming, 360-camera, Ambisonic
Recording philosophy? “Minimalist” - seeks to capture source and soundfield with a single recording array or microphone - generally based on stereophonic technique “Mains + ambience” - main stereo array for source; separate technique to capture ambience in surround “Multi-mic + ambience” - multi-track capture of source + surround ambience
“Minimalist” techniques Same categories as stereo techniques: - coincident: double Mid/Side, Ambisonic - near coincident: Williams Arrays, INA5, & others - spaced: Decca-tree variants: Fukada tree & others Other: - Holophone - Binaural
Williams MMAD
OCT Uses a near coincident trio of mic's for the front Recommends separate rear ambience array
Double MS Cardiods facing forward and back, sharing a bidirectional side. Decoded for 4 or 5 speakers
Holophone Proprietary egg-shaped surround microphones
Ambisonics In theory: 4 coincident microphones: an omni (W), and three bidirectionals X: side, Y: front to back, Z: vertical Allows mid/side pairs in any direction Mono, stereo, and surround compatible Can be rotated, “zoomed”, and flipped Reality: uses a tetrahedral array of 4 cardioid capsules
Binaural
Surround ambience arrays Sources can be captured in multitrack and special arrays can capture the ambience for surround mixing.
IRT Cross Four cardioids at 90 degrees
Hamasaki Square Four bidirectionals, 6 feet apart, aimed 90 degrees off-axis to source for maximum rejection of direct sound