Microphone Characteristics Vital To Know For Sound Reinforcement

Condenser microphones are more complex than dynamics and tend to be somewhat more costly. Also, condensers may be adversely affected by extremes of temperature and humidity which can cause them to become noisy or fail temporarily. However, condensers can readily be made with higher sensitivity and can provide a smoother, more natural sound, particularly at high frequencies. Flat frequency response and extended frequency range are much easier to obtain in a condenser. In addition, condenser microphones can be made very small without significant loss of performance.

The decision to use a condenser or dynamic microphone depends not only on the sound source and the sound reinforcement system but on the physical setting as well. From a practical standpoint, if the microphone will be used in a severe environment such as a rock and roll club or for outdoor sound, dynamic types would be a good choice. In a more controlled environment such as a concert hall or theatrical setting, a condenser microphone might be preferred for many sound sources, especially when the highest sound quality is desired.

Frequency Response
The output level or sensitivity of the microphone over its operating range from lowest to highest frequency.

Virtually all microphone manufacturers list the frequency response of their microphones over a range, for example 50 – 15,000 Hz. This usually corresponds with a graph that indicates output level relative to frequency.

A microphone whose output is equal at all frequencies has a flat frequency response.

Flat frequency response.

Flat response microphones typically have an extended frequency range. They reproduce a variety of sound sources without changing or coloring the original sound.

A microphone whose response has peaks or dips in certain frequency areas exhibits a shaped response.

A shaped response is usually designed to enhance a sound source in a particular application.

Shaped frequency response.

For instance, a microphone may have a peak in the 2 – 8 kHz range to increase intelligibility for live vocals. This shape is called a presence peak or rise.

A microphone may also be designed to be less sensitive to certain other frequencies. One example is reduced low frequency response (low end roll-off) to minimize unwanted “boominess” or stage rumble.

Directionality
A microphone’s sensitivity to sound relative to the direction or angle from which the sound arrives.

There are a number of different directional patterns found in microphone design. These are typically plotted in a polar pattern to graphically display the directionality of the microphone. The polar pattern shows the variation in sensitivity 360 degrees around the microphone, assuming that the microphone is in the center and that 0 degrees represents the front of the microphone.

The three basic directional types of microphones are omnidirectional, unidirectional, and bidirectional.

Omnidirectional microphone.

The omnidirectional microphone has equal output or sensitivity at all angles. Its coverage angle is a full 360 degrees.

An omnidirectional microphone will pick up the maximum amount of ambient sound. In live sound situations an omni should be placed very close to the sound source to pick up a useable balance between direct sound and ambient sound. In addition, an omni cannot be aimed away from undesired sources such as PA speakers which may cause feedback.