As temperatures soar across China this summer, a familiar seasonal soundtrack has become unexpectedly dangerous. Some social media platforms have lately been flooded with complaints from netizens saying that the annual chorus of cicadas seems louder and more relentless than in previous years.

For some, the incessant buzzing has crossed the line from a mere nuisance to a serious medical emergency — leading to confirmed cases of hearing damage in the country.

A report published Saturday by the Linping District Media Center in Hangzhou, East China's Zhejiang Province, said that a patient surnamed Sun woke up in the morning to find that his ears felt blocked and unresponsive to sound stimuli — he could barely even hear his phone ringing.

Sun was later diagnosed with noise-induced high-frequency hearing loss. After inquiring about his daily routine, the doctor determined that the condition was likely sudden deafness caused by prolonged exposure to cicada chirping, the local media reported.

One expert from the Institute of Plant Protection at the Chinese Academy of Agricultural Sciences explained that the extreme heat is the primary culprit for seemingly louder cicadas, according to China Youth Daily.

Persistent high temperatures act like a natural "stimulant" for cicadas, driving them to chirp more frequently and intensely in their urgent search for mates. However, this natural symphony can reach peak decibel levels of over 80 decibels — equivalent to the sustained whine of a power drill. As recent cases reveal, this is enough to harm the human ear, the expert said.

Another case involving an 18-year-old student from Zhejiang, East China's Zhejiang Province, also gained traction. He went camping in the mountains and was exposed to dense cicada chirping for four consecutive hours. After seeking medical treatment, he was diagnosed with temporary noise-induced high-frequency hearing loss, per Ningbo Evening News.

Zhang, a Beijing resident, told the Global Times that he recently went hiking in the mountains west of the city. While he had never paid much attention to cicada chirping on previous outings, this time the noise was so overwhelming that he had to put on his earphones just to keep his focus from being completely consumed by the deafening buzz.

Lei Zhongren, a researcher at the Institute of Plant Protection under the Chinese Academy of Agricultural Sciences, explained that cicada populations also experience boom-and-bust cycles, much like the fruiting cycles of fruit trees.

Cicada populations are constantly changing. Aside from climatic factors, they are also influenced by natural predators, diseases, and other variables. When cicada populations expand, their natural predators tend to catch up — for example, the numbers of entomopathogenic fungi that infect cicadas and certain insect species that specialize in feeding on cicadas increase, which in turn causes cicada populations to decline, Lei told China Science News.

Every summer, the outpatient clinic sees several cases of hearing impairment related to cicada noise, according to a doctor cited by Linping District Media Center, Hangzhou.

Many people hold a common misconception that natural sounds cannot harm the ears. However, in reality, even the pleasant-sounding chirping of cicadas is essentially high-frequency noise. Cicadas can chirp from morning till night, and their calls are highly penetrating and can carry over long distances. The sound waves are concentrated in the high-frequency range of 3,000-8,000 Hz, which directly impacts the cochlea's fragile high-frequency perception cells — making high-frequency hearing the first to be damaged, the doctor said.

A single cicada can produce about 70 decibels, while a chorus of cicadas can exceed the safety threshold of 85 decibels. Prolonged exposure can easily damage the inner ear's hair cells. Once this damage progresses to an irreversible stage, it cannot be restored for life, and patients can only rely on hearing aids for improvement, per the doctor.

Professor Wei Cong from the College of Plant Protection at Northwest A&F University told China Science News that when the population density of cicadas reaches a level that causes significant impacts on agricultural and forestry production and the ecological environment, relevant departments should promptly take scientific prevention and control measures to protect biodiversity while maintaining ecological balance.