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Directional Response

Directional Response. Directional Response. Sensitivity to various angles of incidence with respect to front of the microphone. Polar patterns - 360° around mic Two main categories: Omnidirectional Directional. Pressure. Pressure mics respond to differences in sound-pressure waves.

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Directional Response

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  1. Directional Response

  2. Directional Response • Sensitivity to various angles of incidence with respect to front of the microphone. • Polar patterns - 360° around mic • Two main categories: • Omnidirectional • Directional

  3. Pressure • Pressure mics respond to differences in sound-pressure waves. • These pressure fluctuations can be picked up from any direction. • (Assuming the physical shape of the mic doesn’t interfere.) • Pressure Mic = Omnidirectional Polar Pattern

  4. Pressure-Gradient • Pressure Gradient mics are responsive to the relative pressure differences between front, back, and sides of a diaphragm. • All directional mics are pressure-gradient. • Purely p-g mics are bidirectional (figure 8). • Older ribbon mics

  5. Multiple Directional Patterns • Multiple polar patterns can be obtained from combinations of pressure and pressure-gradient, or from multiple pressure-gradient capsules.

  6. Patterns • Omnidirectional (omni) • Bidirectional (figure 8) • Cardiod (front) • Super-, Sub- and Hyper-cardiod allow for some rear pickup.

  7. Cardiod • Dynamic mics often achieve directionality through use of rear port. (phase delays) • Condenser mics can use two capsules. • In-phase: omni • Out of phase: bidirectional • Variable stepped combinations to achieve varied cardiod responses

  8. Cardiod, sub, super-duper and hyper • Cardiod derives its name from the heart-shaped polar pattern. • Super-cardiod allows for a small amount of rear signal to be captured. • Sub-cardiod has a rounded rear pattern. • Hyper-cardiod allows for greater sensitivity to rear signals, with a wider rear pattern. (approaches bidirectional)

  9. Frequency Response Curve • Measured on-axis, output plotted in dB • Measurement of output over audible frequency range when given a constant signal. • Off-axis plots sometimes included • Flat response (no output variation across frequency range) • More common to have some emphasis or de-emphasis. • De/emphasis can occur due to preamp stage, diaphragm characteristics, tube resonance, windscreen design, etc.

  10. Proximity Effect • All directional microphones exhibit proximity effect. • Low-frequency boost when close to source. • When source is close, gradient properties diminish, with low frequencies favored.

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