Polar and Frequency ResponseFor this discussion, you will chart the frequency response and polar response of one of your microphones. Solve the following issues:1. What source signal will you use

Polar Response

Another factor contributing to a mic's unique response is its polar response; that is, how it responds to sound coming at it from different directions. A mic can either respond to changes in air pressure or in air velocity, or both. The extent to which a mic is velocity or pressure sensitive will determine its polar response. The more pressure-sensitive a mic, the more it will be omnidirectional; the more velocity-sensitive it is, the more it will tend towards a bi-directional response.

Omnidirectional

An omnidirectional mic will respond equally to sound coming from all directions. Because only one side of the diaphragm is exposed, the mic can only sense changes in air pressure, regardless of direction. Note, however, that even omnidirectional mics become more directional at the highest frequencies, responding better to sound coming from directly on-axis to (in front of) the mic that off-axis to (from the sides and especially behind) the mic. This is due to the body of the mic itself acting as a baffle.

Of all polar responses, the omnidirectional tends to exhibit the flattest frequency response, particularly in the lower frequencies. Omnidirectional mics are said to be pressure-sensitive or pressure microphones.

Bi-Directional / Figure-of-8

A bi-directional or figure-of-8 microphone is least sensitive to sound coming from 90o and 270o off-axis (the sides) and most sensitive to sound coming from directly in front of or behind the mic (on-axis and 180o off-axis). A bi-directional mic is also known as a velocity or pressure-gradient mic (see text), as it is fully velocity-sensitive.

Cardioid

Perhaps the most commonly encountered microphones, a mic with a cardioid polar pattern responds best to sound coming from directly on axis (0o ), and rejects sound coming from 180o off-axis (directly behind the mic) the most. It is 50 percent pressure sensitive and 50 percent velocity sensitive. Cardioid microphones are also said to be directional or unidirectional.

Notice that off-axis response is not uniform at all frequencies, and therefore sound reaching the mic from off axis (leakage from other nearby instruments, for example) can sound quite unnatural. This is called off-axis coloration. Typically, the more directional the mic is, the more significant the off-axis coloration, which is then balanced against the need to reject nearby sources of sound.

Hypercardioid

A hypercardioid microphone is even better at rejecting sound coming from the sides (typically 12 dB at 90o and 270o), but slightly less good at rejecting sound coming from 180o off-axis (directly behind the mic). Hypercardioid microphones are said to be highly directional.

Supercardiod

A supercardioid microphone is slightly less directional than a hypercardioid, with a response around -9 dB rather than -12 dB 90o and 270o off-axis. It is also somewhat less sensitive to sound coming from the rear (180o).

Shotgun

The most-highly directional mic is called a shotgun mic, often used in field or location recording to principally capture spoken dialog or other targeted distant sound sources, while effectively rejecting most other sources or noise.