Hype and pseudoscience. I mean, just look at their explanation of the "science" behind it:
The Vagus nerve is a nerve that originates in the brain. NERVANA electronically signals the Vagus nerve which in turn stimulates the release of neurotransmitters in the brain that enhance mood.
I've listened to music through fucking $500 earphones, and I can report that earphone quality makes a big difference. However, quality comes from engineering miniaturized speakers to produce good sound and designing the body of the earphone to transmit sound properly through the tissues of the outer and middle ear, not from this meme-science mumbo-jumbo. Don't waste your money or time on this trash.
https://acls.com/free-resources/tachycar…
You're welcome. First one's free.