Detail the use of upper structure triads and their impact on creating complex chord voicings in jazz harmony.

Upper structure triads are a crucial tool in jazz harmony, providing a means to create complex and colorful chord voicings. They involve adding a triad built from a different scale or mode on top of a pre-existing chord, typically a seventh chord. This technique goes beyond basic chord extensions and adds a layer of sophistication, enabling jazz musicians to create rich and nuanced sounds. The impact of these triads is significant, adding new melodic possibilities, harmonic colors, and increased dissonance, which is typical of modern jazz. The concept of upper structure triads is based on the idea that a seventh chord can have a triad added to it that's not directly from the original key. For example, a G7 chord would normally have extensions such as 9, 11 and 13, which are all derived from the G mixolydian scale (G A B C D E F). An upper structure triad, in contrast, is borrowed from a related scale and stacked on top of this G7 chord. The idea is to add a triad that adds new color and tension. Here are some specific examples to illustrate the use and impact of upper structure triads: 1. G7 with a B major triad (B-D#-F#): A G7 chord already includes the notes G-B-D-F. Stacking a B major triad on ....