Microphone

A microphone is a device that converts sound waves to electric impulses. Various types are available and used for different types of recording or as inputs to audio amplifiers for public address systems sound energy can be converted to electric energy by the use of a microphone. There are a number of types of microphones available today, but we will limit our discussion to three basic types so that you can see the principles on which they work.

When you speak into a microphone, the audio pressure causes a diaphragm to move in line with the pressure applied to it. The diaphragm is attached to the device which causes current to pass or flow in a proportion to the instant pressure that is applied to the diaphragm, the construction of  the carbon microphone where the diaphragm moves the carbon granules back and forth to compress them and change the internal resistance of the carbon material. This in turn causes the current through the resistance (carbon granules) to vary with the pressure generated by the audio striking the diaphragm.

Microphones are rated according to their frequency response, impedance, and sensitiv­ity. For good quality, the electric waves from the microphone must correspond closely to the magnitude and frequency of the sound waves that cause them, so that no new frequencies are introduced. The frequency range of the microphone (range of frequencies over which the microphone is capable of responding) need be no wider than the desired overall response limits of the system with which it is to be used. The microphone device response must be flat or uniform within its range of frequency, and free from any sharp dips or peaks.

The real impedance of the microphone is of significance mainly because it is related to the load impedance into which the microphone will operate. If the load has a high impedance, the microphone should also have a high impedance, and vice versa. Of course, impedance-matching devices may be used between the microphone and its load

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• What is Microphone? Explain.