Constant buzzing, humming and ringing - 24 hours a day, seven days a week. Some 4 million Germans suffer from tinnitus, which can make life difficult.
For some, it's like a pneumatic drill, while others may feel they have a washing machine throbbing inside their head. Those suffering from tinnitus - from the Latin “ringing” - are often unable to satisfactorily describe their symptoms. And no one's really able to help: For they are the only ones who can hear the sound in their ears.
"It's not an acoustic noise that can be measured," Gerhard Goebel explained in an interview with Deutsche Welle. He is the director of the German Tinnitus League, a self-help group. "Even if we disconnected the acoustic nerve, so basically separated the ear from the brain, the noise would remain. So it's a phantom sound," Goebel said.
Chronic or temporary?
Within the first three months, the underlying causes can often be treated. But some 250,000 people are newly diagnosed with chronic tinnitus every year.
There are two types of tinnitus: compensated and decompensated. Some 3 million Germans suffer from the compensated variety, which only surfaces occasionally. Patients register the sound but manage to compensate, or offset, it.
About a million patients suffer from the more severe, decompensated type: a relentless noise, which deeply affects the patient's quality of life.
Yet tinnitus - just like pain - is not classified as an illness, but rather a symptom. The never-ending noise can, however, result in recognised diseases, such as depression or paranoia.
Noise and stress
Tinnitus is often caused by continuing noise or an acoustic shock, such as an explosion. These account for a third of the cases. According to the German Tinnitus League, another major cause is stress.
Kurt Hembold used to work as a sales manager. With his exhausting, stressful job, since 1996 he's been subjected to a constant humming noise.
"Imagine you're standing under an overhead power line in summer. You can hear a very high-pitched whistling noise - that probably describes my symptoms best," Hembold told Deutsche Welle.
Since 1998, Hembold - who is in his early 70s - has been leading a self-help group in Bad Laer, a small town in northern Germany. His wife, as well, suffers from tinnitus.
It's all in the brain
Our hearing system is a very complex network, highly sensitive to disturbance. Injuries can permanently damage internal hair cells or the cochlea, which muffle sounds.
Once the inner ear is damaged, it may send erroneous messages to the brain. "As far as we know, these faulty connections are amplified in the brain. Stress and ear damage then make noises worse," said Goebel.
Many diseases, such as hearing impairment, can trigger tinnitus. As people are no longer able to distinguish surrounding noises, tinnitus takes center stage.
In some cases, a hearing aid can alleviate tinnitus: as more natural sounds reach the ear, they compete with the rushing and ringing noises. It's a way distract the brain from the tinnitus, Goebel said.
Living with tinnitus
Hembold has learnt to live with the humming in this head. Sometimes, when it keeps him awake at night, he turns the radio on. Complete silence is the worst, he said, because there's no other noise to distract from the humming and rushing in his head.
"It's like a candle in a pitch-black room," Goebel explained. "You're unable to ignore the light. But when I open a window or turn the lights on, then I can no longer make out the candle that well."
Many young people are unable to deal with tinnitus, Hembold says. Sometimes, young sufferers tell him that they would rather jump off a bridge than live with the symptoms. "That makes you realize the extent of their suffering."
Modern cockpit doors have safety systems to keep out intruders. They can be opened from the cabin - to help pilots in emergency. But control is from within. And that has its own dangers.
The tech sector in the UK is booming, but tech startups are hungry beasts that need constant feeding. A worsening technology skills gap means many tech companies just can’t find the talent to feed their own growth.
From outer space to the ground: Analyzing high-resolution images from satellites, new research proves how prevalent the impact of deforestation and the fragmentation of forests is. But there’s still a way out.
In their final declaration, delegates underlined their commitment to pledges made in London last year. But the outcome also sparked anger among some conservation groups.