Lust & Fangs: Steamy Vampire Erotic Short Stories
About halfway through class she turned to him and smiled devilishly.
"Hi there." She didn't speak out loud, her lips never moved and he instead heard her voice inside his head. "My name is Syn, you must be new at this." The voice giggled a little. "You can't even Whisper yet, can you?"
Syn noticed the perplexed look on his face. "It's like ventriloquism, but at ultra-high frequencies. Just hum a little, keep making it higher until you can feel it." Mike followed her orders until he reached a frequency that no human could her. "Now just talk."