So, this curious message popped up in my email just now, from the US Embassy in Beijing.

Location: Guangzhou

Event: A U.S. government employee in China recently reported subtle and vague, but abnormal, sensations of sound and pressure. The U.S. government is taking these reports seriously and has informed its official staff in China of this event. We do not currently know what caused the reported symptoms and we are not aware of any similar situations in China, either inside or outside of the diplomatic community.

Action to Take:

If you have concerns about any symptoms or medical problems that developed during or after a stay in China, consult a medical professional.
While in China, if you experience any unusual acute auditory or sensory phenomena accompanied by unusual sounds or piercing noises, do not attempt to locate their source. Instead, move to a location where the sounds are not present.

Weren’t there reports of similar disruptions at other embassies?