They fled from the Ukrainian battlefront, but the hum of drones persisted in pursuit.

In a cramped apartment in the Ukrainian capital Kyiv, Pavlo, a 30-year-old drone operator who had recently returned from the front, unzipped a black case about the size of a pizza box. Inside, there was a four-rotor drone he intended to fly around the room.

He pressed buttons on the control unit and pushed the antenna to different positions. Nothing happened. “Sorry, not today,” he said, with a smile. The unit looked fine, but something was broken.

At the front, Pavlo, who asked to be identified only by his first name, was a pilot of first-person view (FPV) drones. These small, highly manoeuvrable drones have front-facing cameras that allow them to be flown remotely. Over the past year or so, bomb-laden FPVs have become ubiquitous on the frontlines in Ukraine, replacing the heavy weapons that characterised the war’s first phase.

The FPVs chase armoured vehicles, hunt infantry units through treelines and stalk individual soldiers to their deaths. “You cannot hide from the FPV, and to run is useless,” Pavlo said. “You try to be as calm as possible, and you pray.”

Even when an FPV is too high to see clearly, or hidden behind foliage, soldiers can hear its distinctive, high-pitched whine.

“Bzzzzzzzzzzzz,” Pavlo said. “You are being hunted.”

After more than a year at the front, Pavlo has returned home to the Kyiv apartment he shares with his wife. But the sound of the drones has followed him. Everyday mechanical tools like lawnmowers, motorcycles and air conditioners remind him of the FPVs that hunted him and his unit mates.

And nature is not an escape. Pavlo can no longer hear the sound of bees and flies buzzing near him without a creeping panic. “I don’t like to go into nature anymore and hear this sound, because it reminds me so hard of the drones,” he said.

Trauma associated with sound is not new – generations of soldiers have been affected by sudden noises after returning to civilian life. But as the war in Ukraine has evolved into a conflict driven by drone technology, the trauma has evolved with it.

“Over the past year, the majority of patients – if they are not physically wounded – have mental health injuries as a result of being under drone activity,” said Dr Serhii Andriichenko, chief psychiatrist at Kyiv’s military hospital. “We call this droneophobia.”

Many thousands of men are now returning from the front like Pavlo, with acute stress disorders associated with the sounds of drones, Dr Andriichenko said. The droneophobia can be triggered by an array of ordinary urban sounds – small motorcycles and scooters, lawnmowers, air conditioners – anything mechanical that whirrs.

“If it’s a moped or a lawnmower, my first thought is that it might be a drone,” said another returned frontline soldier, Savur, who lost his arm in an FPV drone attack.

At the front line the drones were a “permanent sound”, said Savur, who in accordance with military protocol asked to be identified by his callsign. “The sound of a shell lasts just a few seconds, but the sound of the drone is there most of the time,” he said.

“You can lay in your position, in your foxhole, and listen to it for hours. I remember that sound all of the time.”

Or sometimes the problem was the opposite – silence. “Silence is always the start,” Dr Andrizenko, the psychiatrist, said. “When the soldiers go on rotation to combat positions, they start listening carefully to make sure there are no drones. There is constant tension, constant fear. They are always looking up.”