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. 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

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

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

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

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

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)

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.

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.