Tritone: The Devil in Music
In classical music, the tritone is a harmonic and melodic dissonance and is important in the study of musical harmony. The name diabolus in musica ("the Devil in music") has been applied to the interval from at least the early 18th century. People were actually executed "back in the day" for writing songs that used this interval.
Because of that original symbolic association with the devil and its avoidance, this interval came to be heard in Western cultural convention as suggesting an "evil" connotative meaning in music. Today the interval continues to suggest an "oppressive", "scary", or "evil" sound and is known colloquially as "The Devil's Interval".
The theme features prominently in the 1949 film Portrait of Jennie, and is used as a musical motif for the ethereal heroine played by Jennifer Jones.
The theme opening Claude Debussy's Prélude à l'après-midi d'un faune outlines a tritone (between C♯ and G) Play