question:  How does it seem that the aliens communicate?
context: Outside, the stars were as before: tiny, myriad points of light, infinitely far away. In his mind's eye he could see it, slowly wheeling, like a second satellite, about the Earth; endlessly gathering knowledge into its insatiable mechanisms. He could see, too, the level on level of laboratories and storerooms that filled its interlocking segments; the meteor deflectors, the air renewal system, the mighty engines at the stern—all the children of his brain. The ship would be filled with the sounds of busy men and women, wresting secrets from the reluctant ether. "The peoples of the world, then, know what they are, and know that we face the most momentous struggle in our history. "Since the Invaders first appeared in Wood River, Oregon, 24 hours ago, they have not once acknowledged our attempts to communicate, or in any way taken notice of our existence as reasoning beings. They have treated us precisely as we, in less enlightened days, might have treated a newly-discovered race of lower animals. They have examined us, dissected us, driven us mad, killed us with no discernable provocation; and this is more intolerable than any normal invasion. "I have no fear that the people of Earth will fail to meet this challenge, for there is no alternative. Not only our individual lives are threatened, but our existence as a race. It was a street scene in the Science City of Manhattan, flooded by the warm spring sunshine. There were left only two blood-red, malignant monstrosities somehow defiling the air they floated in; and below them, a pitiful huddle of flesh no longer recognizable as human beings. This isn't like a war, where the noncombatants' morale has to be kept up. The viewpoint of the teleo sender changed as the two red beings soared away from their victims and angled slowly up the street. The Invaders were floating up the sloping side of a tall, pure white structure that dominated the rest.
output:  They speak telepathically, in a language people can't understand.
options:  They make mental contact with human victims, often leading them to madness.  They speak through people, making them scream.  Their lips are sealed together. They are unable to speak.  They speak telepathically, in a language people can't understand.