The enactment of the Clean Air Act of 1970 (1970 CAA) resulted in a major shift in the federal government's role in air pollution control. This legislation authorized the development of comprehensive federal and state regulations to limit emissions from both stationary (industrial) sources and mobile sources.
Polyphony began and musical rules changed
The tritone is argued as a musical interval composed of three adjacent whole tones. It is often defined as an interval spanning six semitones. it led to the disregard of traditional tonality.
