A Synthesizer is generally any kind of electronic musical instrument, or electronic device capable of producing or manipulating audio tones, such as musical notes, through audio signal processing.
Synthesizers work by manipulating electrical signals which appear as sound when they are used to drive audio amplifiers. These tones are generated by electrical circuits which may work by manipulating a signal through a series of oscillators and filters in an analog circuit (as in analog synthesizers), or may perform mathematical manipulation of signals using a microprocessor and digital signal processing (as in digital synthesizers), or by a combination of both methods. Synthesized sounds may sound dramatically different than recordings of natural sounds, though sampling synthesizers significantly blur this distinction.
