Other than her song, Nerissa offers the man no resistance or encouragement.  She does find that the sensations that are now coursing through her body has changed the timbre of her voice.  It still has the same sweet tones, but there is a richness which now threads itself through the song, low and seducing.  As though she knows this will hurry the process and once his tires, he will leave her in peace and she will be able to escape.