Justin Kurtz explains the technical theory behind the spaced omni microphone technique.
On March 3, 2010, Hartt School of Music Professor and Music Production and Technology Program Chair Justin Kurtz lead a presentation titled "The Spaced Omni Mic Technique Explained".
Kurtz began with a review of the fundamentals of stereo micing, covering theory on sound localization and phantom imaging. Justin explained how coincident, near-coincident, and spaced techniques create an "illusion of reality" when played back through studio monitors. Data was presented on the psychoacoustic effects of varying amplitudes and delay times between left and right signals, and practical implementations of these findings were investigated by considering the effects of SRA (sound recording angle), distance from source, and microphone polar patterns.
Kurtz explained limitations of directional microphones often used in stereo recordings, highlighting issues in frequency and phase response. "We forget that when we pull out a cardioid mic there's all this baggage than comes with it." He challenged students to opt for techniques that call for onmi-directional patterns, presenting a magnificent example of an orchestral spaced-omni recoding.
