Why do few people rent hotel rooms nowadays? Most corridors use 18-megapixel cylindrical network cameras that clearly support audio environmental noise filtering and 3D digital noise reduction. The image and sound are clear, very suitable for security monitoring. They can hear every move in the room, including moans, hums, and even breathing, and instantly match the heard sounds to convert them into text subtitles. Many unscrupulous hotels make a lot of money by selling small videos with text and sound. And some hotels, in order to make money, deliberately leave large gaps under the doors during renovation, specifically so that the corridor monitoring AI intelligent noise reduction can clearly hear recordings of breathing sounds.