Well keep in mind, the binaural beats in hemisync are not really there! there is no low frequency being heard by the ears. The 'beats' are being produced within your brain, as a result of the part of your brain that analyses sound trying to match up 2 slightly different tones.

This would seem to preclude any effects from frequencies being imposed from outside - it is your brain that constructs the effects that bring about the entrainment of your mind. Other than that, all you are hearing is 2 separate tones & I would guarantee that if you listened to either one of them alone (just hold one headphone to your ear at a time) there will be no strange effect.

It is only when you listen to both & your brain does it's mix & match that you get the effect. that's part of why it takes 6 - 7 minutes for the entrainment effect to start. And why you can't get the effect from external speakers - in that instance, both sounds are reaching both ears & there is no binaural beat.

(And yes, I've seen a thread here where someone claimed to get an effect from speakers but for mine, that shows the effects of expectation rather than entrainment. Entrainment has been measured with EEG monitoring & it is a real effect. But it is in the brain that it all happens.