The woman, who's since been identified as Ms. Chen, had gone to bed with ringing in her ears, only to wake up to her silent boyfriend.
Upon further investigation, and ear, nose, and throat specialist at Qianpu Hospital told Ms. Chen (the patient has only been identified by her last name) she was suffering from reverse-slope hearing loss, a form of low-frequency hearing loss. After thinking she could sleep it off, she awoke next to her boyfriend, unable to hear him.
The doctor examined her and said Chen was able to hear her, but couldn't hear a male patient who spoke to her as well.
As for why Chen suffered the loss, Dr. Xiaoqing is unsure, but believes it was brought on by stress and long days of working. In reverse-sloping hearing loss, the shape of the audiogram runs in the opposite direction. It can affect one in almost 13,000 patients with hearing problems.
As well as struggling to hear low-frequency voices, those with the condition can find it tough to make out voices on the phone, as well as noises like the hum of the fridge or thunder.
Low frequency hearing loss can be very risky for people as it can affect their ability to hear things like the low hum of an oncoming vehicle.
Although there are a number of causes of reverse-slope hearing losses, the most common causes are genetic abnormalities, Wolfram syndrome and Mondini dysplasia. 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. That figure is expected to rise to over 900 million by 2050.
It has been linked to genetics and can be triggered by certain diseases (for example, Ménière's disease) and viral infections.
This condition hinders Chen's ability to hear low frequency sounds, such as the average grown man's voice.