Microphones that are used most of the time are unidirectional or omnidirectional. The music artists who use microphones for conventional purposes employ the microphones according to their needs. Unidirectional microphone is a perfect instrument for one speaker or someone who is using a solo instrument.
Unidirectional microphones are the ones, which catch the music when the sound is aimed at its center. Omnidirectional microphone, on the other hand, can pick up sounds from any direction. The electronic pick up, which captures the sound, is placed in center of a mesh-covered dome.
The basic purposes of the omnidirectional microphones are same that are to receive vibrations from outside sources of music, and convert them to electronic signals. One of the discrete identification of the omnidirectional microphone is their distinctive rounded end.
A heavy mesh bulb inside the mesh covered dome, which gives protection to the sensitive electronics, is the heart of the mic. If outside particles or potentially unwanted objects enter the filament of the mic, it will cause disturbance in the working of the mic. The capturing of the music will be disrupted; as well the quality will get distorted. The mesh acts as a filter and lets only the sound element enter through it. Sometimes, a foam rubber shield is also used to give extended protection.
This foam rubber shield has another propose, that is to bar the wind and heavy breathing noise. One of the major concerns for omnidirectional microphone is the capture of the ambient noise. The thick wire mesh usually minimizes this problem also.
When a group of singers or instrumentalists performs, they use the omnidirectional microphone instead of the other variations. The mic is placed in a top position, like suspending from a ceiling, to facilitate picking up of the music. The instrumentalists who are in the group, for example, choral group, vocalist, pianist or guitarist, can place the mic in a position, which suits best.
In case of solo vocalists, they can use the omnidirectional microphones and still get the amplified effects. Unidirectional microphones, on the other hand, needs to be positioned in a suitable arrangement and the musicians and speakers are needed to seat accordingly.
One of the major drawbacks of the mic is that being a non human device it cannot differentiate between wanted and the unwanted sound or music. So, most of the times, the environmental sounds are also captured and amplified like the music. There are musicians and performers who want the background noise of the audience to be amplified but more often than not this is unwanted part of the recording. Unidirectional mic, however, is best suitable in picking up the foreground music only and not the backgrounders.
There are other problems, too, that a performer needs to take into account in case of the omnidirectional microphones. If the mic is placed near the speaker it has the chance of picking up irrelevant sounds, which get amplified by the mic and produce awkward noise. However, keeping all the drawbacks in mind, the mic creates more solution than the problem it creates.