I think this is probably a Neptune in Aquarius thing: music for healing rediscovered for a new age; I hadn't heard of Solfeggio Harmonics till just recently, but according to this website:
the original sound frequencies were used in Ancient Gregorian Chants, such as the great hymn to St. John the Baptist, along with others that church authorities say were lost centuries ago. The chants and their special tones were believed to impart tremendous spiritual blessings when sung in harmony during religious masses. These powerful frequencies were rediscovered by Dr. Joseph Puleo as described in the book Healing Codes for the Biological Apocalypse by Dr. Leonard Horowitz.
The Six Solfeggio Frequencies include:
UT – 396 Hz – Liberating Guilt and Fear
RE – 417 Hz – Undoing Situations and Facilitating Change
MI – 528 Hz – Transformation and Miracles (DNA Repair)
FA – 639 Hz – Connecting/Relationships
SOL – 741 Hz – Awakening Intuition
LA – 852 Hz – Returning to Spiritual Order
For example, the third note, frequency 528, relates to the note MI on the scale and derives from the phrase "MI-ra gestorum" in Latin meaning "miracle." Stunningly, this is the exact frequency used by genetic biochemists to repair broken DNA – the genetic blueprint upon which life is based.
I don't understand all that to be honest, but it's an interesting read; anything that stresses the importance of energy and vibration and wavelengths is ok with me (and it's oh so Aquarius, I feel, that squiggly symbol of Aquarius and the idea of wavelengths). There's lots of examples on YouTube of this music, which is uber relaxing and has the most fabulous images to go with it, and I can recommend the Source Vibrations album as pretty much the best music I've heard to use in healing sessions. There's definately something about this stuff that goes beyond it being just sweet and soothing. Here's an example of the relationships one, the 639Hz, have some of this to heal your frazzled nerves: