Low frequency modulation: you want it in your audio sessions, even if you don't want music. Why?
It lets you bake-in a control track for any music-reactive sex toy. Value added, experience enhanced.
Plus this is also how you make custom binaurals. THREAD!

Start with a bass loop. It can be VERY simple. Here I'm using my fav bass rack, but any synth bass will do. For this exercise, simpler is better. You don't even need to vary the note. Get in in there so we can get started.

Next we want to put a filter on it. No presets! Later on you can tweak other parameters, but right now we care about one, and only one: frequency. This sets our cutoff: frequencies above that value will be filtered out. At the start we turn it all the way up so it filters NOTHING

You can tinker with the rest of the parameters to find a sweet spot you like. For this purpose I like slow attack and a pretty steep envelope (pictured above). Once set, we are leaving those alone. Freq is the main thing, and we're automating the heck out of it.

Start with 1 loop of your bass part and go a bit crazy. Here I set freq points on one loop and copied it over, then reversed the curves on the automation. I can copy and paste this pattern across a whole track, but first:

Distortion! Any distortion, tube, or amp emulator plugin will do. Any preset will do. This is entirely up to you. Distortion with more noise is easier to "bury" in a mix. We're also automating this, but just the mix of wet (with distortion) to dry (no distortion).

And that's it! You can copy and paste this across a whole track, or mix it up with the envelopes. To bury this in the mix you can just roll the fade VERY low. Do NOT use a low frequency cut on EQ: we need to keep this audio information, even if it's barely audible, BECAUSE....

Variations in low spectrum frequencies are how software-controlled toys react to "music". We just created something for a toy to react to that has a steady rhythm but pretty wild tonal variation. That's not all we created, though. You're halfway done with a new binaural beat.

You DID get the MFreeFXBundle like I said to, right? Of course you did. I was just testing you.
Here's the link anyway. https://www.meldaproduction.com/MFreeFXBundle 

Boom. Fx plugins for miles.
The one we want next is "autopan".
Duplicate your subsonic bass track, put autopay on both of them. Enable Sync on both plugins, depth to 100. Set one track to 1/4 and disable distortion plugin. Set the other track to 1/2 and turn up the noise. Done.

You can layer higher frequency pulses on top of what you now have, but this is a solid foundation. You can automate the sync rate on the autopan to create depth and energy variations, but this is 90% of the way there.

When mixing for toy control, think of it this way: a vibrator is basically a subwoofer, and vice versa. Anything that would kick in a sub will kick in a toy in a sub (haha).

This is just intended to get you started. Theres a lot of options for creative expression in the enveloping and what parameters you automate even on a one-note bass track. Have fun!