The Frequency Effect is a science fiction novel that draws from proven science to provide a pseudo-real storyline. Every area of the storyline was researched to make it as entertaining and realistic as possible from the very beginning.
The main crux of the story, the thought that technology devices resonate at the frequency of the human brain, isn't a surprising as you might think. It all stems from the concept of entrainment that was devised by electricity pioneer Nikola Tesla - the inspiration for the car brand Tesla. He was fascinated by the way in which all objects resonate at a particular frequency. He showed that by aligning the frequency of one with another, it was possible to match its frequency. He went further to show that he could take down buildings by putting an oscillator next to them and matching their frequency.
It was then interesting to consider how the entrainment of the mind can happen. The first point to consider is that, just like every other object, the brain resonates at a particular frequency. In fact, the brain resonates at different frequencies dependent on mood. This article outlines them clearly - Beta, Theta, Alpha, Delta. It wasn't too much of a stretch to think that devices might be able to change the frequency and therefore 'dumb' the senses.
The story highlights how Ben manages to control The Frequency Effect and, in fact, harness lucid dreams to gain a better view of reality. You might be surprised but there are many machines designed for this process. It sounds like science fiction but they are actually real and there are many reviews to prove it. I haven't tried them myself though, so I am as skeptical as you may be. Have a read here if you would like to learn more.
A final point, is that music forms a key part of the story, particularly when pushing Ben over the edge. This is also an area that is supported by significant scientific research. Monroe in fact took Tesla's theories of entrainment and adapted them to the brain. You can see in this scientific study that entrainment using music has been used in the treatment of many disorders. There are many words of warning in doing so, so please remember the story is a work of fiction. Don't actively try it at home.
I hope that provides a view for the background to the story. It was always meant as a work of fiction, so please don't believe it to be real.