The Fifty-Hertz Frequency

On a Saturday at ten at night, a functional twenty-two-year-old girl should be in a heated bar complaining about the price of craft beer, answering the message from Marcos that had been floating in her inbox for three days like an exquisite corpse or, at the very least, having warm feet.

Instead, I was sitting on a concrete block at the old breakwater of Bahía Serena, squeezing between my thighs an aluminum thermos full of tea that already tasted like metal and defeat, with the Totoro sticker peeling at the corners.

"If you get hypothermia, I'm not dragging you," Aldara said. Crack. Another sunflower seed shell shot out toward the Atlantic. "I'm leaving you here for the seagulls to eat. Or the illegal percebeiros. Whichever gets here first."

"Seagulls don't eat human carrion if there are hake discards, Aldara. They have standards."

"You haven't seen the new port seagulls. They carry switchblades and have criminal records."

I sighed and pulled up my hood. Aldara was wearing her uncle Gonzalo's yellow oilskin, two sizes too big, and hadn't taken it off since the funeral. Nobody in town had dared ask for it back, so I didn't either. I shoved my hands into the torn pockets of my parka.

When I rested my palm on the iron railing that closed off the technical access to the breakwater, a crust of orange rust and dry saltpeter crunched under my frayed glove, releasing a gritty dust that the damp wind easily scattered.

"Come on, contemporary sound art genius," Aldara insisted, shaking the nearly empty bag of sunflower seeds. "Explain to me again why we can't record the ocean from the Nautical Club terrace while we have two coffees with orujo. The ocean is the same. It goes splash, then it goes shhh, and then it depresses you."

"The Nautical Club has a beer compressor that makes noise at seventy hertz and a waiter who cleans glasses singing Melendi," I replied without taking my eyes off the digital VU meters. "This is for the end-of-term assignment. I need the surf crashing in the low cavities, not some gas station pop remix."

"Melendi has respectable tracks. The one about the moon and the violin."

"Please, shut up."

"I'm shutting up, but let the record show you owe me a plate of bravas."

I turned the gain potentiometer of the portable recorder by a millimeter. My headphones—an old pair with padded headbands held together by black electrical tape along the arch and a rebellious cable that only transmitted signal through the left ear cup—protested with a harsh crackle. Condensation. The fog rolling in from the open sea clung to everything like a wet spiderweb: to my eyelashes, to the copper jack connector, to the screens of the anchored ships in the distance that blinked like sickly eyes.

On the phone screen, the preview of a draft note read:

"Marcos, I don't think going out again is a good idea because you want to talk about our future and I don't even know what I'm having for dinner tonight, besides the fact that it drives me crazy how you chew ice."

I tapped the screen with my frozen thumb, erased the text letter by letter until the cursor was blinking over nothing, and locked the phone.

Two hundred meters out to sea, over the blunt silhouette of the old lighthouse, the north wind sneaked through the cracks of the copper sheets of the blind lantern, producing a dull, hollow, and steady whistling, almost like air escaping through the neck of a giant bottle. That lighthouse had been dismantled since before we were born; a mass of gray granite that the City Council wouldn't tear down due to lack of budget and that the fishermen ignored like a drunk relative at a wedding.

Nobody fears a dead lighthouse until a deaf machine learns to listen to what the fog prefers to keep quiet.

I had written that phrase on the first page of my field notebook in spiky handwriting, convinced it sounded poetic for the project's report, but now, with the salty air burning my nose and the pungent stench of fermented seaweed in the block's cracks mixed with the burnt diesel of the fishing boats, it just seemed pretentious.

I adjusted the analog dial again. Five decibels more. Six.

A flat, regular hum of exactly fifty hertz settled into the left channel of my headphones. It wasn't the ocean.

I blinked. I furrowed my brow.

"Aldara."

"What? Are we done yet? Can I order the bravas?"

"Don't move. Stop chewing."

"Hey, salt keeps me alive, don't take away my only comfort."

"Seriously, stay still for a second."

I closed my eyes, pressing the working earpiece hard against my left ear. Behind the electrical hum—that harmonic typically caused by a faulty ground on a damp transformer—there was something else. A rhythmic, metallic oscillation, a kind of slow drag that went up and down like a piston's breath.

The fishing dock was at my back, wrapped in a mist so dense that the sodium vapor streetlights were barely yellowish smudges staining the milky air against the broken windows of the old fish auction warehouse. Nobody was fishing at that hour.

"Are you hearing space whales or what's wrong with your face?" Aldara teased, stretching her legs out over the concrete. Her heel struck a stone with a dry snap. "You look like a constipated owl."

"There's a modulated carrier wave in the low frequency," I muttered, more to myself than to her. "Like someone has a shortwave transmitter turned on at the base of the lighthouse. But the tower hasn't had an electrical hookup since the nineties..."

"Come on, let me hear that." Aldara dropped the empty seed bag, which the wind immediately swept away toward the waves, and leaned toward her with a crooked little smile. "I'm sure it's Radio María sneaking through the wet cables. The last time you got this mysterious, you spent ten minutes recording the baker's van fan."

"Don't touch the connector, it wobbles if you—"

It was useless.

Aldara yanked the headphones off my head with a nimble tug, laughing with that smug laugh of someone who has spent their whole life tearing down the technical obsessions of serious people. She jammed the left side of the earpiece against her ear, letting the right one dangle limply against her freckled cheek.

"Let's see, mysteries of Bahía Serena presents..." Aldara began to joke in an affected newscaster voice.

Then she stopped.

Her laughter didn't cut off all at once; it unraveled slowly, as if her jaw had run out of hinges.

The yellowish hue of the dock streetlights seemed to suddenly leap onto the skin of her cheeks, leaving her with a whitish, dull tone beneath her freckles. Her fingers, holding the plastic arch wrapped in electrical tape, went completely still.

"Aldara?" I sat up on the stone block, alarmed by my friend's sudden rigidity. "What's wrong? Is it interference?"

In the headphones, filtering through the condenser membrane soaked in saltpeter, the fifty-hertz hum had given way to a heavy, damp breathing, followed by two dry raps against a microphone and a harsh, cavernous throat-clearing that came from the bottom of a chest punished by dark tobacco.

A throat-clearing that ended with a brief, asthmatic whistle as she swallowed air.

Aldara lowered her hand with mechanical slowness, but she didn't take the earpiece out of her ear. She stared at the dark mass of the blind lighthouse, outlined barely as a thicker shadow against the Atlantic fog.

"That noise," Aldara said, and her voice came out so thin the wind almost ate it whole.

"What noise?"

"That throat-clearing, Candela."

Silence.

"Aldara, what are you talking about?"

"It's Uncle Gonzalo," she whispered, her eyes glued to the rusted door of the unlit lantern. "It's the throat-clearing he always did before serving coffee."

Uncle Gonzalo had been dead for four years according to court paperwork, buried in a sea that never returned his boat.

And he had just cleared his throat thirty meters away from us.