Shannon explained, as you can find on the MHS 5.5G sales page, that different tracks may have varying effectiveness. I recommend reading up on it.
So in your case, you appear to be more resistant than the average person by default, and the trickling stream (and ocean surf) has a different, more quiet way of sending information compared to the ultrasonic, which is louder. This is irrespective of the volume you choose. You may interpret the masked tracks as suggestions and not as orders, and you subconsciously find the former more comfortable, while with the latter you refuse to comply.
If you're getting better results with trickling stream, or at least seeing more signs of you being affected as you do now, keep on it, and the same for future subliminals you use as well.
So in your case, you appear to be more resistant than the average person by default, and the trickling stream (and ocean surf) has a different, more quiet way of sending information compared to the ultrasonic, which is louder. This is irrespective of the volume you choose. You may interpret the masked tracks as suggestions and not as orders, and you subconsciously find the former more comfortable, while with the latter you refuse to comply.
If you're getting better results with trickling stream, or at least seeing more signs of you being affected as you do now, keep on it, and the same for future subliminals you use as well.
