The first step in modern sound amplification is to convert sound vibration, which is a form of acoustical or mechanical radiant energy, into electrical energy. This function is performed by the microphone. Sound waves, which are actually variations in air pressure, are converted by the microphone into a corresponding electrical voltage that varies in frequency and strength according to the "pressure" of the sound vibrations. Microphones are necessarily delicate instruments and should be given special care.
Since the output of the microphone is a very minute electrical voltage or signal, that signal must be strengthened or amplified many thousands of times in order to "drive" a loudspeaker. For this purpose, an audio amplifier is used. Many amplifiers have provision for receiving the signals from several microphones or other sources, combining them, and then amplifying the combined program to the power required for the audience to hear easily. Occasionally a separate pre-amplifier is used to increase the low-level signals from the microphones, mix them together and then distribute the combined program to any point, near or far, where it can be further amplified as needed. Large sound systems may utilize many amplifiers, each working to supply the program to a specific area, where the audience may consist of a few persons or many thousands.
Finally, the amplified electrical signal is fed into one or more loudspeakers. The loudspeaker acts as a sort of microphone in reverse. A cone or a diaphragm is set to vibrating by the amplified electrical current. Electrical energy is thereby converted into mechanical energy, setting up vibrations in the adjacent air once again with sound waves that are audible to our hearing.
Since the output of the microphone is a very minute electrical voltage or signal, that signal must be strengthened or amplified many thousands of times in order to "drive" a loudspeaker. For this purpose, an audio amplifier is used. Many amplifiers have provision for receiving the signals from several microphones or other sources, combining them, and then amplifying the combined program to the power required for the audience to hear easily. Occasionally a separate pre-amplifier is used to increase the low-level signals from the microphones, mix them together and then distribute the combined program to any point, near or far, where it can be further amplified as needed. Large sound systems may utilize many amplifiers, each working to supply the program to a specific area, where the audience may consist of a few persons or many thousands.
Finally, the amplified electrical signal is fed into one or more loudspeakers. The loudspeaker acts as a sort of microphone in reverse. A cone or a diaphragm is set to vibrating by the amplified electrical current. Electrical energy is thereby converted into mechanical energy, setting up vibrations in the adjacent air once again with sound waves that are audible to our hearing.
