Klausner looked down at the box, then at the Doctor, and he reached up and began gently to scratch the lobe of his right ear. There was a pause. The Doctor stood by the door, waiting, smiling.
'All right, I'll tell you, if you're interested.' There was another pause, and the Doctor could see that Klausner was having trouble about how to begin.
He was shifting from one foot to the other, tugging at the lobe of his ear, looking at his feet, and then at last, slowly, he said, 'Well, it's like this ... the theory is very simple really. The human ear ... you know that it can't hear everything. There are sounds that are so low-pitched or so high-pitched that it can't hear them.'
'Yes,' the Doctor said. 'Yes.'
'Well, speaking very roughly any note so high that it has more than fifteen thousand vibrations a second - we can't hear it. Dogs have better ears than us. You know you can buy a whistle whose note is so high-pitched that you can't hear it at all. But a dog can hear it.'
'Yes, I've seen one,' the Doctor said.
'Of course you have. And up the scale, higher than the note of that whistle, there is another note - a vibration if you like, but I prefer to think of it as a note. You can't hear that one either. And above that there is another and another rising right up the scale for ever and ever and ever, an endless succession of notes ... an infinity of notes ... there is a note - if only our ears could hear it - so high that it vibrates a million times a second ... and another a million times as high as that ... and on and on, higher and higher, as far as numbers go, which is ... infinity ... eternity ... beyond the stars.'
Klausner was becoming more animated every moment. He was a frail man, nervous and twitchy, with always moving hands. His large head inclined towards his left shoulder as though his neck were not quite strong enough to support it rigidly. His face was smooth and pale, almost white, and the pale-grey eyes that blinked and peered from behind a pair of steel spectacles were bewildered, unfocused, remote. He was a frail, nervous, twitchy little man, a moth of a man, dreamy and distracted; suddenly fluttering and animated; and now the Doctor, looking at that strange pale face and those pale-grey eyes, felt that somehow there was about this little person a quality of distance, of immense immeasurable distance, as though the mind were far away from where the body was.
The Doctor waited for him to go on. Klausner sighed and clasped his hands tightly together. 'I believe,' he said, speaking more slowly now, 'that there is a whole world of sound about us all the time that we cannot hear. It is possible that up there in those high-pitched inaudible regions there is a new exciting music being made, with subtle harmonies and fierce grinding discords, a music so powerful that it would drive us mad if only our ears were tuned to hear the sound of it. There may be anything ... for all we know there may -'
'Yes,' the Doctor said. 'But it's not very probable.'
'Why not? Why not?' Klausner pointed to a fly sitting on a small roll of copper
wire on the workbench. 'You see that fly? What sort of noise is that fly making now? None - that one can hear. But for all we know the creature may be whistling like mad on a very high note, or barking or croaking or singing a song. It's got a mouth, hasn't it? It's got a throat?'
The Doctor looked at the fly and he smiled. He was still standing by the door with his hands on the doorknob. 'Well,' he said. 'So you're going to check up on that?'
'Some time ago,' Klausner said, 'I made a simple instrument that proved to me the existence of many odd inaudible sounds. Often I have sat and watched the needle of my instrument recording the presence of sound vibrations in the air when I myself could hear nothing. And those are the sounds I want to listen to. I want to know where they come from and who or what is making them.'
'And that machine on the table there,' the Doctor said, 'is that going to allow you to hear these noises?'
'It may. Who knows? So far, I've had no luck. But I've made some changes in it and tonight I'm ready for another trial. This machine,' he said, touching it with his hands, 'is designed to pick up sound vibrations that are too high-pitched for reception by the human ear, and to convert them to a scale of audible tones. I tune it in, almost like a radio.'
'How d'you mean?'
'It isn't complicated. Say I wish to listen to the squeak of a bat. That's a fairly high-pitched sound - about thirty thousand vibrations a second. The average human ear can't quite hear it. Now, if there were a bat flying around this room and I tuned in to thirty thousand on my machine, I would hear the squeaking of that bat very clearly. I would even hear the correct note - F sharp, or B flat, or whatever it might be - but merely at a much lower pitch. Don't you understand?'
The Doctor looked at the long, black coffin-box. 'And you're going to try it tonight?'
'Yes.'
'Well, I wish you luck.' He glanced at his watch. 'My goodness!' he said. 'I must fly. Good-bye, and thank you for telling me. I must call again sometime and find out what happened.' The Doctor went out and closed the door behind him.
For a while longer, Klausner fussed about with the wires in the black box; then he straightened up and in a soft excited whisper said, 'Now we'll try again ... We'll take it out into the garden this time ... and then perhaps ... perhaps ... the reception will be better. Lift it up now ... carefully ... Oh, my God, it's heavy!' He carried the box to the door, found that he couldn't open the door without putting it down, carried it back, put it on the bench, opened the door, and then carried it with some difficulty into the garden. He placed the box carefully on a small wooden table that stood on the lawn. He returned to the shed and fetched a pair of earphones. He plugged the wire connections from the earphones into the machine and put the earphones over his ears. The movements of his hands were quick and precise. He was excited, and breathed loudly and quickly through his mouth. He kept on talking to himself with little words of comfort and encouragement, as though he were afraid - afraid that the machine might not work and afraid also of what might happen if it did.
He stood there in the garden beside the wooden table, so pale, small, and thin that he looked like an ancient, consumptive, bespectacled child. The sun had gone down. There was no wind, no sound at all. From where he stood, he could see over a low fence into the next garden, and there was a woman walking down the garden with a flower-basket on her arm. He watched her for a while without thinking about her at all. Then he turned to the box on the table and pressed a switch on its front. He put his left hand on the volume control and his right hand on the knob that moved a needle across a large central dial, like the wavelength dial of a radio. The dial was marked with many numbers, in a series of bands, starting at 15,000 and going on up to 1,000,000.
And now he was bending forward over the machine. His head was cocked to one side in a tense, listening attitude. His right hand was beginning to turn the knob. The needle was travelling slowly across the dial, so slowly he could hardly see it move, and in the earphones he could hear a faint, spasmodic crackling.
Behind this crackling sound he could hear a distant humming tone which was the noise of the machine itself, but that was all. As he listened, he became conscious of a curious sensation, a feeling that his ears were stretching out away from his head, that each ear was connected to his head by a thin stiff wire, like a tentacle, and that the wires were lengthening, that the ears were going up and up towards a secret and forbidden territory, a dangerous ultrasonic region where ears had never been before and had no right to be.
The little needle crept slowly across the dial, and suddenly he heard a shriek, a frightful piercing shriek, and he jumped and dropped his hands, catching hold of the edge of the table. He stared around him as if expecting to see the person who had shrieked. There was no one in sight except the woman in the garden next door, and it was certainly not she. She was bending down, cutting yellow roses and putting them in her basket.
Again it came - a throatless, inhuman shriek, sharp and short, very clear and cold. The note itself possessed a minor, metallic quality that he had never heard before. Klausner looked around him, searching instinctively for the source of the noise. The woman next door was the only living thing in sight. He saw her reach down; take a rose stem in the fingers of one hand and snip the stem with a pair of scissors. Again he heard the scream.
It came at the exact moment when the rose stem was cut.
At this point, the woman straightened up, put the scissors in the basket with the roses and turned to walk away.
'Mrs Saunders!' Klausner shouted, his voice shrill with excitement. 'Oh, Mrs Saunders!'