Live electronic music (also known as live electronics and electroacoustic improvisation) is any kind of music that can include the use of electroacoustic instruments, various electronic sound-generating devices, and computers, but which generally excludes the use of prerecorded or sampled material. Initially the practice developed in reaction to sound-based composition for fixed media such as musique concrète, electronic music and early computer music. Musical improvisation often plays a large role in the performance of this music. The timbres of various sounds may be transformed extensively using devices such as amplifiers, filters, ring modulators and other forms of circuitry . Widespread adoption of mobile computing has led to an increase in the use of computers in live electronics. Real-time generation and manipulation of audio using laptop computers is now commonplace. Electronic musicians often play partially pre-recorded music in Live PAs.