Beginning about 1950, two leading groups began experimenting with electronic music, one in Cologne and the other in Paris. The product of the latter group was referred to as musique concrète in acknowledgement of the principle that preexisting, or “concrete,” recorded sounds serve as the basis of all sonorities in the finished work. The basic sounds, which may be derived from any source—musical, natural, or mechanical—are modified electronically and arranged in any combination and succession suitable to the composer’s purpose. The German group, led by Karlheinz Stockhausen, was concerned with a purer form of the medium in that its basic sounds are electrically generated instead of being recorded from sources external to the electronic apparatus. The two approaches share one connecting link with music of the past: all sounds have pitch, intensity, duration, and quality. All other concepts of musical organization have been discarded, including the necessity of a performer. Electronic compositions exist on a tape (or disc), and can be made audible by a speaker system. The dehumanizing of music has been carried several steps further by the use of mathematics and even of computers to determine the nature of sound materials—either electronic or that produced by more conventional means—and their organization. At the other extreme is aleatory music, in which the performer is allowed to choose the manner and order of presentation of materials specified or simply suggested by the composer.

Popular music

Another result of advances in electronics has been the tremendous growth of popular music during the 20th century. New techniques have made possible high-fidelity reproduction of sound and its widespread and rapid dissemination through radio, phonograph, tape recorder, and television. In addition, some of the instruments used in popular music have incorporated electronic amplification as well as sound production. While there has been a popular music as long as mankind has turned to singing and dancing for diversion and recreation, much of it was folk music and existed only as an oral tradition. But popular music in the modern sense originated in the late 18th century, when ballads made popular in ballad opera and dance music received wide circulation. The same types flourished throughout the 19th century and into the 20th, when a new direction was prompted by the emergence of jazz among blacks in the southern United States. After the original ragtime came jazz proper, swing, bebop, and rock in its numerous manifestations—punk, new wave, etc. Early in the century, the novelty of jazz rhythms and dominance of brass, woodwind, and percussion instruments over strings attracted some serious composers who occasionally incorporated suitable jazz idioms into their works. Since about 1930, the influence has worked in both directions, and popular music has gradually adopted techniques that originated in serious music. Regardless of the interaction of popular and serious music, the popularity of the former is one of the most significant musical developments of the 20th century, especially in view of the widening gulf between the serious composer and the potential audience.

It is impossible to arrive at a complete and objective description of a revolutionary movement while it is in progress; only a period of time can provide the necessary perspective. It can be acknowledged, however, that music has never before passed through a more anarchic phase than in the 20th century. The tremendous number and diversity of stylistic distinctions has precluded a characteristic designation for the first half of the century, but one must be forthcoming, for musicians of the future will need the terms modern and contemporary for their own times.

Despite the disproportionate publicity given to the most radical experiments, the majority of leading composers working today continue along the moderate path established in the late 1920s and 1930s. And, if one can rely on the lessons of history, the mainstream of music will continue to absorb those new techniques that contribute to expressiveness and communication while discarding that which is merely novel and sensational, so that music history will remain an evolutionary rather than a revolutionary process.