Barbara Ann Brennan in her book Hands of Light talks about how, when she was very young, she would go into the forest and sit quietly for hours, waiting for small animals to come to her. In those times, she would sit very still and try to blend into her surroundings.
It was not till much later that she came to realize the significance of those times - which essentially is what almost all meditation and the practice of stillness and silence is about - that in those moments, she entered into an expanded state of consciousness where she was able to perceive the energy field around objects. This later became what she called HSP and what she used in her healing practice. She does state that to develop HSP, one has to enter into an expanded state of consciousness.
This practice of silence also ties into Eckhart Tolle's practice of 'becoming conscious and aware of the Now" and Wayne Dwyer's meditation of "going into the gap". Dwyer uses the term "gap" where Tolle prefers the term "space". In either case, they refer to the same thing. Which is all very interesting as once again, it demonstrates the inter-connectedness of so many things.