I swear by this.
The 'high pitched frequency and/or tone'.
I start out just as many others.
Quiet space, back straight, hands in lap together palms up, no music.
As you begin to relax, the easiest way down is to focus on your breathing. I'm sure you've heard that already, and I'm sure you've heard how to go down your body relaxing each piece.
You probably haven't been told to listen for the high pitch frequency. Find it. It's there. Once you find it, the goal is to raise its volume or intensity. Then the goal is to bring that sound from whichever side it's on, and bring it to the middle of the brain so that you're hearing it with 'both your ears'.
You can get crazy sensations from harmonic vibrations when you do this.
One thing I've learned about meditation is that there are several different ways of several different combinations of several different techniques you can use to achieve...several different things.
I'm not even sure what this frequency is supposed to do. I did not learn it from a yogi, I simply discovered that it was a fantastic way to shut out or completely forget about my jabbering mind. 'Working with' these frequencies/tones, is an easy way to silence your 'monkey-brain'. I've achieved some pretty profound states using this method, and I know I've only barely scratched the surface.
Try it and lemme know what you think