Klausner’s titular sound machine, which he uses to hear notes that human ears can’t normally discern, symbolizes the dark underbelly of scientific progress, suggesting that some scientific advancements may effectively rob humanity of its innocence. This can be seen in Dahl’s frequent, often morbid, use of children in his imagery. The machine is first introduced to the reader as being similar in shape to “a child’s coffin.” In gesturing to a death of a child, Dahl is suggesting that Klausner’s machine will be the death of Klausner’s innocence and that, more broadly, some scientific discoveries are better left unearthed. Later, when testing out his machine, Klausner resembles a “consumptive, bespectacled child.” The word consumptive means “affected with a wasting disease” and thus suggests that the machine has a corroding, corrupting influence on Klausner’s childlike innocence.
Klausner speculates as much when he explains to the Doctor that he believes there are notes out there that “would drive us mad if only our ears were tuned to hear the sound of [them].” Later, when Klausner finally finishes tinkering with his machine and straps on his headphones to test it out, he has the most peculiar feeling that he is venturing into “dangerous” and “forbidden territory”—a place “where ears had never been before and had no right to be.” Rather than be hemmed in by timidity, though, Klausner ignores these dark warnings and continues with his experiment. When Klausner becomes convinced that his machine works and that plants emit screams of pain when they’re hurt, he grows even more frantic and unhinged than before. He agonizes over the pain he’s inflicted on plants for the sake of his experiment—especially a large beech tree in the park, which he’s gouged with an axe. Despite this seemingly genuine remorse, Klausner still presses on with his project and severs the tree irreparably in the hopes of proving to the Doctor that plants do emit these sounds and feel pain. With the tree’s destruction, it seems like the machine’s influence has made Klausner violent and sadistic (even if regretful) as he continues to destroy plants with increasing severity just to keep hearing their cries. Fittingly, the severed branch crushes Klausner’s machine, which seems like Dahl’s definitive assessment that some discoveries—like this one—are better left unmade, but that the damage has already been done to Klausner, to the machine, to the tree, and perhaps also to the Doctor.
The Machine Quotes in The Sound Machine
It was a warm summer evening and Klausner walked quickly through the front gate and around the side of the house and into the garden at the back. He went on down the garden until he came to a wooden shed and he unlocked the door, went inside and closed the door behind him. The interior of the shed was an unpainted room. Against one wall, on the left, there was a long wooden workbench, and on it, among a littering of wires and batteries and small sharp tools, there stood a black box about three feet long, the shape of a child's coffin.
All the while he kept speaking softly to himself, nodding his head, smiling sometimes, his hands always moving, the fingers moving swiftly, deftly, inside the box, his mouth twisting into curious shapes when a thing was delicate or difficult to do, saying, “Yes…Yes…And now this one…Yes…Yes…But is this right? Is it—where's my diagram?…Ah, yes…Of course…Yes, yes…That's right…And now…Good…Good…Yes…Yes, yes, yes.” His concentration was intense; his movements were quick; there was an air of urgency about the way he worked, of breathlessness, of strong suppressed excitement.
“It’s just an idea.”
“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 forever 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.”
He plugged the wire connections from the earphones into the machine and put the earphones over his ears. The movement 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. […] 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 toward a secret and forbidden territory, a dangerous ultrasonic region where ears had never been before and had no right to be.
From the moment that he started pulling to the moment when the stem broke, he heard—he distinctly heard in the earphones—a faint high-pitched cry, curiously inanimate. He took another daisy and did it again. Once more he heard the cry, but he wasn't so sure now that it expressed pain. No, it wasn't pain; it was surprise. Or was it? It didn't really express any of the feelings or emotions known to a human being. It was just a cry, a neutral, stony cry—a single emotionless note, expressing nothing. It had been the same with the roses. He had been wrong in calling it a cry of pain. A flower probably didn’t feel pain. It felt something else which we didn't know about—something called toin or spud or plinuckment, or anything you like.
He tried to remember what the shriek of the tree had sounded like, but he couldn’t. He could remember only that it had been enormous and frightful and that it had made him feel sick with horror. He tried to imagine what sort of noise a human would make if he had to stand anchored to the ground while someone deliberately swung a small sharp thing at his leg so that the blade cut in deep and wedged itself in the cut. Same sort of noise perhaps? No. Quite different. The noise of the tree was worse than any known human noise because of that frightening, toneless, throatless quality. He began to wonder about other living things, and he thought immediately of a field of wheat, a field of wheat standing up straight and yellow and alive, with the mower going through it, cutting the stems, five hundred stems a second, every second. Oh, my God, what would that sound be like? […] no, he thought. I do not want to go to a wheat field with my machine. I would never eat bread after that.