I had a sister who was very brave and and didn't fear ghosts or believe in them, and would try to find evidence on them.
One day she wanted to visit a hotel that was believed to be haunted to some extent. She stayed in a room of that hotel.
However, a strange sound saying "抬头,抬头,抬头...." would come. The language was not familiar to her, so she couldn't understand what it said. This continued for days, and she wasn't able to sleep well.
Finally, one day she decided to thoroughly search the hotel. She checked every room, looked inside all closets and cupboards, searched under tables, chairs etc., but couldn't find anything. The sound "抬头,抬头,抬头...." was still coming, and it became louder, but seemingly started to fade away. She was tired and angry and tried to go to sleep, it seemed like the was nothing she could do.
The next morning, she woke up and thought about the incident. Surprisingly, the sound was not there anymore, not even once; it was a quiet morning. Finally, she realized what it was, and left the hotel at once (horrified, also convinced that ghosts are real).
What is so suspicious in this story?
I have added a hint for searching a complete anwer . By the way , the answers I have received till now already has the complete answer , but couldn't show it correctly :) . The answer also, is very simple to find !
Hint 1 :- What is so special about the sound , even if it cannot be traced by searching every drawers , closets , and under tables , chairs etc. ?