A synthesizer is an electronic instrument capable of proucing a variety of sounds by generating and combining signals of different frequencies. A modern digital synthesizer uses a frequency synthesizer microprocessor component to calculate mathematical functions, which generate signals of different frequencies. There are three main types of synthesizers, which differ in operation: analog, digital and software-based. Synthesizers create electrical signals, rather than direct acoustic sounds, which are then amplified through a loudspeaker or set of headphones.