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Using Pressure and Gradient to Derive Microphone Patterns

Using Pressure and Gradient to Derive Microphone Patterns . Audio Days 2011 Paris. David Josephson Josephson Engineering, Inc. Santa Cruz, California. Scalars and Vectors. nondirectional/pressure/scalar responds to pressure from any direction directional/pressure-gradient/vector

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Using Pressure and Gradient to Derive Microphone Patterns

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  1. Using Pressure and Gradient to Derive Microphone Patterns Audio Days 2011 Paris David Josephson Josephson Engineering, Inc. Santa Cruz, California

  2. Scalars and Vectors • nondirectional/pressure/scalar • responds to pressure from any direction • directional/pressure-gradient/vector • responds to difference in pressure between two points

  3. Pressure Response

  4. Pressure Response

  5. Pressure Gradient Response

  6. Pressure Gradient Response

  7. Cardioid pattern + =

  8. What is B-Format? • signal format for Ambisonics • W – omnidirectional (pressure) • X – figure-8 (cos ) facing front-to-back • Y – figure 8 facing side-to-side • Z – figure 8 facing up-to-down

  9. Native B-format • omnidirectional mic produces W signal • front-facing bidirectional mic produces X • side-facing bidirectional mic produces Y • (optional) up-down mic for Z

  10. Set pattern with ratio of W to X a + b cos() a ... is how much of the omni (W) b ... is how much of the fig-8 (X)

  11. + = X + Y = another figure-8 ...pointed at an angle corresponding to the ratio of X and Y

  12. 5.1 from B-format • FC = aW + bX (where a/b sets pattern) • FL = aW + bX + cY • FR = aW + bX - cY • SL = aW - bX + cY • SR = aW - bX - cY • LFE = low passed W

  13. Josephson C-700S

  14. Y W X

  15. Billy Pitrone – guitar and vocal Sarah Eblin – bass and vocal Pete Hicks – fiddle, mandolin and vocal Rob Horgan – banjo Recorded by Dave Nielsen at Rancho Armadillo, Santa Cruz www.beancreekbluegrass.com

  16. Anna Clyne, rewind Cabrillo Music Festival Orchestra, Marin Alsop, director Recorded by Cuco Daglio www.cabrillomusic.org

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