In astrology the aspects of planets can be represented as musical chords… two or three notes played in unison. Sometimes these tones blend well and sound good, while at other times they do not. When they sound bad - note they will be challenging energy.
Scientist Johannes Kepler in the 1600's established correlations between astrological-aspects and consonances-of-music. A trine, is an aspect of planets in which they are 120 degrees apart and looks like they are arranged in a triangle. This creates a relationship of 360:240 or 3/2, which is the mathematical equivalent of a musical fifth.
If the frequencies of several planets sound dissonant or nasty to you, perhaps there is another tone to blend with them so they sound harmonious. This transforms a challenging horoscope to a pleasant one! In another application of this idea, if you meet a person who annoys you, can analyze their birth tones and select another tone that enables you to harmonize with them. Sing or hum this tone and watch your feelings about this person change.
In ancient times, when people analyzed a child’s astrology to select a marriage partner, they were seeing if their fundamental tones were harmonious, making a marriage a positive experience! Music and subtle energy of the stars can be useful in a surprising number of ways!