After Dr. Lin Xiaoqing checked out her symptoms, she was able to identify that she could not hear deeper voices due to their lower frequencies.
After Chen went to a specialist ear, nose and throat doctor (ENT) she was diagnosed with a condition called "reverse-slope hearing loss".
At the hospital, she told doctors she had gone to sleep with "nausea and ringing in her ears", and had risen the next morning to find that she was unable to hear her boyfriend speak.
"She was able to hear me when I spoke to her, but when a young male patient walked in, she couldn't hear him at all", Dr. Xiaoqing says in a story with the Daily Mail.
She added that she believes the recent stress and exhaustion Ms Chen had been under could have contributed to the condition. This explains why hearing loss more often affects our ability to hear higher-pitched sounds than lower-pitched ones, she said.
Anyone who suffers from low-frequency hearing loss, generally, can't hear noises that have a frequency of 2,000 Hz or below. "Doctors will call it hearing loss, I call it evolution", wrote one person on Twitter. Because of the way it is shaped on an audiogram - a diagonal slope from the top left-hand corner to the bottom right-hand corner - it gets its name, ski-slope.
The good news is that when RSHL is detected quickly, chances are good that the hearing loss can be reversed, Kraskin said. Autoimmune disorders that affect the inner ear - which are thought to occur in about 1 percent of the US population - may also be a cause of RSHL, Clark said. It can also be caused by changes in the pressure of the fluid in the inner ear, endolymph, which itself can be the result of spinal or general anesthesia, intracranial hypertension, and a perilymphatic fistula.
According to the World Health Organization, around 466 million people across the world are affected by some kind of hearing loss.
Reverse-slope hearing loss caused a Chinese woman to only hear female voices.
It has been linked to genetics and can be triggered by certain diseases (for example, Ménière's disease) and viral infections.