Yes these things are real and powerful, best if listened to with headphones. There are different frequencies you can listen to for different desired outcomes. The most important, imo, is you first need to allow yourself to let them work. By that I mean like believe in it so to speak. Your mind is very powerful and these are simply tools at our disposal that can enhance us if we let them. Think of what happens when you put rice or sand above a speaker, our bodies act in the same way based on the frequencies around us.

Speaking of Rife, Matthew Rife has a machine (very expensive) but my friend told me it actually works well. See the link below as well as Rife's twitter handle, he has good info he puts out almost on a daily basis. Hope this helps kind of answering your question

https://realrifetechnology.com/

https://twitter.com/RifeTechnology