From the 50s science has checked and proven, that extra low frequency waves between 5 and 30 hertz are carriers for telepathic transmissions. They found this also in alien bodies that were rescued from several crashes, their evolved consciousness is always running in this range and these beings use telepathic messages as their normal.
So let’s have a view at human brain waves, here Theta and Alpha are the range for this type of language. But you also know, that humans are ordered to run in high beta for their awaken state. As result they will never see the needed frequencies and that’s more worse in high beta they have unlimited noise from their intellect in the head. If you hear voices without break, you are unable to listen to telepathic messages from outside. How will you decide between intellect noise and outer messages? Simple answer: You can’t until you leave the destructive beta state, calm down to theta and alpha where the intellect is silent, here you are ready to receive and able to send.