Yang Junfei knows the vulgar habits of his own club member very well, likes to talk half of his speech, and never looks at whether the situation is critical or not, until he has whetted people's appetites, this will reveal the mystery. He had a request for help, so he had to echo in a low voice, "Of course it's the latter." ”

"Of course, I'm the latter. After listening to my friend's story, I went to what he called the lab. Night Silence still spoke slowly, and his tone was full of banter, "And guess what, I saw the same thing that night." There was really a shadow forming around it, at the edge of the line of sight. It was terrifying, and even my heart was beating with fear. I turned around, and the gray shadow disappeared immediately. However, I like to persevere. I spent the whole night looking around the house for the reason, and finally, I found the answer! ”

There was a little smugness in Ye Bu's voice, "I found out that all this was done by a large fan in the laboratory." When that fan is running, it emits infrasound waves that are inaudible to the human ear. Low-frequency infrasound waves can make people breathe short, make people feel uneasy, and produce a lot of weird feelings. Infrasound waves can also have an effect on human vision, and may even cause strange hallucinations. ”

"The reason why I see gray shadows take shape, like ghosts in horror stories. In fact, the reason is very simple. "What humans see out of the corner of their eyes is actually monochrome, so under the influence of infrasound, I saw gray objects suddenly appear." When I turned my head to look at it, the thing disappeared from the lens. This is because the central part of the optic membrane filters light at low spatial frequencies. The frequency of infrasound waves is extremely low and can only cause the inner ear canal to vibrate slightly. Many animals can hear it, but humans can't. This is the truth about my friend's encounter! ”

Yang Junfei was stunned for a long time, "Wait, Xiaoye, does this matter have anything to do with the case I am holding now?" ”

"Alas, don't you usually say that you are so smart that you are at the top, why haven't you understood it now. It really makes me doubt your IQ. The night on the other end of the phone sighed silently, "First of all, there are so many laboratories in the world, and most of them are equipped with large fans. No, the same fans are used in a wide range of industries. Why are the infrasound waves produced by fans in so many places not received by the human brain, giving people the illusion of hell? And what happened to my friend's lab? The answer to this question is also very simple, the frequency of infrasound! Maybe the frequency has to be a certain degree of alignment before people hallucinate. ”

After a slight pause, he said silently, "Old man, there is one thing that needs to be affirmed in your case this time, that is the reason why the incident happened is in the first and second classes of Yue Yunxue's high school, and the eight people who died in the school are all related to this classroom." If this proposition is a formula, assuming that x is the classroom and the deceased is y, then the cause of death z is equated. Since the classroom has been identified as a problematic factor, why and how it is problematic is the focus of your next investigation. ”

"Well, well, I'll definitely give priority to this." The old man tucked the phone between his shoulder and ear, and took out his notebook to record Xiaoye's words.

"Another point, the reason why I tell this story is actually very valuable for you." Ye Bu continued to say: "Why are those who die often on duty? What did the rest of the students in that class who had died by accident or suicide in the past two months have done? This is also something that needs to be clarified. However, I do have some ideas. Li Yang, the second and third class of high school you mentioned, went insane and bit people everywhere after helping the female classmates in the first and second classes of high school to do their duty work. This means that their over-the-top things often happen in the morning, when many people don't come. Of course, except for Feng Xue, who died today, is an exception. However, in terms of probability, we have to consider what a person did when he came to the classroom in the morning! ”

"yes, what did they do more? The work of the day students is generally simpler. I cleaned up the day before, and I didn't have much work in the morning! "Yang Junfei has also studied Yue Yunxue, so he naturally knows the system of this school very well.

"No, they did do one more thing." It is not difficult to imagine that Ye Buyu smirked proudly on the other end of the phone, and even grinned in his signature meaningful mouth, "There is one thing I guess you don't care about at all." When you were telling the story of the incident, I checked the local news in Nose City. I came across a message by chance. ”

"The climate in Nose City this year is very strange, hot day by day and cold day by day, and the temperature has soared to about 28 degrees just after the Spring Festival. This makes the closed environment of the school a breeding ground for harmful bacteria. Therefore, for the sake of children's health, the local government requires that the ceiling fans on the doors, windows and ceilings be opened every morning before entering the classroom to pump out harmful gases and bacteria. ”

"And the time, exactly two months ago."

"Ahh Yang Junfei trembled, he had vaguely heard about this matter, and the matter of turning on the fan every day was done early in the morning. Think about it carefully, in addition to today's Feng Xue, there is only this one that ordinary students on duty have done. It took more than 10 minutes to turn on the ceiling fan for ventilation, and then it would be closed before the students entered the classroom one after another.

"You mean, there was a problem with a ceiling fan in the first and second classes of high school, which emitted infrasound waves, and then caused the students on duty that day to hallucinate, and finally caused him to die?" The old man's nervous mouth was dry, and he asked cautiously.

"It's hard to explain, but that's the most likely guess right now." Ye Buyu said lightly, "Since I was not at the scene, all I heard were your one-sided words." There is no way to provide more advice. However, it would be much better to start with this aspect for the time being. ”

"That's true." Yang Junfei nodded secretly, "But if that's the case, then why have only eight victims appeared in two months?" ”

"Infrasound waves that obviously affect the brain are not so easy to form, and they are affected by the voltage frequency, air density, atmospheric density and drag at that time. However, there have been eight accidents in two months, and the odds are already very high. "Ye Bu Si is very helpless about his boss's lack of knowledge.

"Well, I'll start with the ceiling fan first." Yang Junfei hurriedly hung up the phone, and then rushed towards the principal's office at the speed of his butt being burned.

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