Nightmare Tower by Sam Merwin — Read

Sitting there alone, waiting for something to happen, Lynne for the first time since becoming aware of her telepathic powers began to get a sense of direction along with the thoughts that came to her from outside. Heretofore she had only been conscious of the thoughts themselves, varying in power according to the strength of the thinker.

Perhaps because of the altitude of the tower-room, perhaps because her own power was increasing with practise, perhaps because telepathy was easier in the thinner Martian atmosphere than on Earth -- perhaps through a combination of all these factors, Lynne was aware of tremendous mental strength.