There are different types of microphone and diverse ways of classifying them. Here, we will look at the polar patterns and diverse technologies available.
Microphones are designed with one purpose in mind, converting acoustic energy into electrical energy and as part of the process, they use a diaphragm. Now that the common ground has been pointed out, the concentration will be shifted to the differences.

Basically, there are 5 different types of microphone technologies:

• Carbon: Carbon dust was used by the earliest microphones for the purpose of identifying audio signal. Telephones used this type of microphones and still, they can be found in some of the telephones available today. In this case, carbon dust is used for the purpose of running current through and the carbon is compressed as a result of the fluctuating current as sounds waves hit the diaphragm.
• Crystal: In this type of microphone the crystals used change shape as a result of electrical properties change. A diaphragm is attached to crystal and the crystal creates a signal once the diaphragm gets vibrated by sound.
• Ribbon: In this type of microphone, a strong magnetic field is used for the purpose of suspending a thin metal wire. Current flowing through this is changed as the ribbon is moved by sound waves. This means that rather than this type of microphone responding to air pressure, it responds air velocity.
• Dynamic: In this case, the diaphragm is designed to move between 2 magnets (positive and negative) once hit by sound waves and because of this movement, a small current is created.
• Condenser: This type of microphone has been around for over a century and it requires external voltage which is also known as phantom power. The backplate and diaphragm create a capacitor. There is a varying capacitance because of the relation between the backplate and the diaphragm.

Polar pattern is the next category used to differentiate microphones and this refers to uniqueness of the region around the microphone from which audio signal gets picked up. In this case, there are 5 categories as well:

• Cardoid: Directly in front of the microphone there is strong sensitivity and this is coupled with rejection from behind and good sensitivity at the sides. (as shown in Fig)
• Supercardoid: Same as cardoid with the slight difference of reduced sensitivity around the sides. There is a small area behind the microphone that includes the pickup range (as shown in Fig)
• Hypercardoid: It is an exaggeration of Supercardoid with the sides sensitivity reduced and the rear featuring increased sensitivity (as shown in Fig). It is more direction than the other 2 cardoid patterns and as such used when maximum sound isolation between sources is needed.
• Omnidirectional: It equally picks up sound from all directions. It is the only one that is not affected by proximity (low range undesirable interference whenever a source of sound is close to the microphone)
• Bidirectional: This is ‘figure 8’ pattern which means sound gets picked equally from opposing directions. The sides do not show any sensitivity (as shown in Fig). In an interview direction, this microphone proves to be useful.

Conferences are important events which are held for varied reasons and attended by a large number of people. Due to this nature of conferences; specialized recording equipment may be required to capture audio recordings for the event. A number of venues do provide built-in recording systems which more than often present technical difficulties during the recording process. There are ways to enhance the clarity of recorded sound using the available recording system.

The first and most important step is to seek the services of an audio equipment expert; if you do not know how to handle the equipment. Have the professional test and check the recording equipment to figure out whether it is fully operational. If the equipment does no work, you may have to hire large scale recording equipment for the event. It is advisable to go for digital recorders because of the high quality sound they record.

Carry out several test recordings before hand to ensure that the equipment work as required. Select an uncompressed digital format to record the sound in. Compression has the tendency to reduce the quality of sound which is never desirable. Set the audio channels to appropriate levels in order to record clean sound free from distortions.

Assign separate microphones to key speakers to ensure that the clearest sound is recorded. You can also go for lapel microphones, if your funds allow it, to record clear audio from each key speaker at the conference.

When the conference day materializes; counter check that the equipment works before officially beginning the conference. Set up the microphones in proximity to key speakers and adjust the levels accordingly. Ask for special consideration from those attending the conference, and those in the vicinity of the conference venue, to maintain minimal noise levels. Noise is the number one cause of bad sound recordings. A conference cannot be recaptured or re-recorded and this is part of the reason why you have to make sure that everything is set up and fully functioning before the conference commences.

Have back up plans; microphones are bound to fail, black outs may be experienced and other technical glitches with the equipment may occur. Have extra microphones, batteries, battery chargers and go for a venue to a backup power source. Respond calmly and professionally when technical difficulties are experienced because the crowds at such events react in line with what they see. Have handy people around to quickly address any technical difficulties which may arise. More on audio transcription