In earlier tonal styles augmented fifths often appear as passing notes or appoggiaturas, as in the first example below. Their characteristic sound comes from the stacking of two major triads and the resulting symmetry means that all the inversions sound the same. This ambiguity was exploited by composers later in the ninenteenth century such as Franz Liszt. The augmented fifth is treated with great freedom in classical and popular genres of the twentieth century.
The augmented fifth overwhelmingly appears with major triads, so it most often appears in chords I, V and IV. With V, it can add extra colour to a dominant seventh chord, although this is rare in earlier tonal styles.
information and orientation as you browse around TonalityGUIDE.com
© Copyright Thomas Pankhurst