Chapter 538: Chapter 537: Sleep Promotion Device

"Feifan, this music production studio that broke down the rain sound file is a pretty big deal in Jingcheng..."

On the terrace, Zeng Ni copied files from a flash drive to the laptop Tian Yu had brought, all while bragging about her accomplishment.

"Their recording studio... I’m not saying it’s the absolute best in Jingcheng, but in terms of advanced equipment, it’s easily in the top ten..."

"How much did it cost?" Yan Feifan cut in, getting straight to the point.

Zeng Ni’s eyes crinkled with a smile. "Well, it didn’t cost any money, but I do owe a friend a *huge* favor."

Yan Feifan just gave a soft "oh."

Zeng Ni waited a moment, but when Yan Feifan offered no further reaction, she stressed again, "A *really*, *really* big favor."

"And in this day and age, owing someone a favor is the hardest kind of debt to repay."

Noticing that Yan Feifan was starting to play dumb and fiddle with the computer, ignoring her, Zeng Ni grew anxious.

She huffed, "Yan Feifan, aren’t you supposed to say something like, ’Since you incurred a favor for me, I’ll owe you two in return?’"

Without even looking up, Yan Feifan replied, "I already repaid you for that favor."

He added, "Yan Jiaojiao’s surgery."

"What? How does that count?"

Zeng Ni protested, "That was a public cosmetic surgery for Yan Jiaojiao! You were basically doing it for your own benefit."

"At most... at most, that counts as half a favor."

"You still owe me half, which rounds up to one whole favor!"

"Fine, I owe you a favor!"

Yan Feifan’s reply this time was surprisingly quick and decisive.

He agreed so readily because he’d just discovered that the studio had turned the decomposed melody and frequency files into a small application. It allowed him to mix and match them freely.

It was clear the music studio had put a lot of thought and effort into it, which Yan Feifan felt was worth the price of another favor.

Song Yi, leaning in next to Yan Feifan, also got a quick look at the application as he clicked through it.

She said in surprise, "That clip of rain we just heard could be broken down into seven melodies and twenty-one frequencies?"

"It all sounded the same to me."

A satisfied Zeng Ni quickly explained, "That’s what you call ’to each their own specialty’! Those guys have incredibly sharp ears."

"A gust of wind could blow by, and they’d be able to pick out nature’s beautiful harmonies within it."

Just then, Yan Feifan randomly clicked on one of the melodies, and the sound of rustling rain emerged from the laptop.

After listening for a while, he clicked another melody.

It was still the sound of rustling rain.

Yan Feifan listened intently for a moment, trying to tell the difference.

But being completely tone-deaf—an audiophile’s nightmare—he really couldn’t distinguish it from the previous one.

"Can you guys hear the difference between these two rain sounds?"

In response to Yan Feifan’s question, Yan Ziruo, Shu Lei, Mr. Tian, and Mrs. Tian all shook their heads, looking perplexed.

Song Yi said, a little uncertainly, "I think it sounds a bit... denser than the last one."

"Yeah, Mr. Yan, it sounds denser to me too," Tian Yu echoed.

Yan Feifan nodded. "As long as you can hear a change, that’s good enough."

He then pulled down the frequency list and clicked on the highest frequency option.

The hertz level of this audio clip, extracted from the original rain sound file, was somewhat surprising to Yan Feifan. It reached an incredible 20,260 Hz.

This high frequency was a glaring outlier in the list. The second-highest frequency plummeted dramatically to 8,600 Hz.

The range of frequencies humans can perceive is between 20 and 20,000 hertz. This is known as the audible range.

The human ear is most sensitive to sounds between 1,000 and 3,000 Hz, as this is the primary range for human speech.

However, Yan Feifan also knew that for sounds below 20 Hz or above 20,000 Hz, while our ears can’t hear them, our bodies can still perceive them.

To reproduce a complete auditory experience, some exceptionally precise recording equipment can even capture low and high-frequency sounds that fall outside the range of human hearing.

Yan Feifan had a theory. ’This anomalous 20,260 Hz audio probably isn’t the sound of rain. It might be some unknown background noise accidentally captured during the recording.’

’Perhaps it’s this accident that gives the rain sound its hypnotic effect.’

’After all, many major discoveries in the history of science have come from accidents, coincidences, or as byproducts of failed experiments!’

Brimming with anticipation, Yan Feifan clicked on the highest frequency audio track and began to carefully experience it.

Because this exceeded the range of human hearing, Yan Ziruo, Mrs. Xia, Mr. Tian, and the others present couldn’t hear a thing.

Under the bright lights of the terrace, they could only see Yan Feifan with his eyes slightly closed, his expression focused as if he were listening intently.

Nearly a minute passed when suddenly, a CRUNCHING sound broke the silence.

Tian Yu, who had just started chewing on an apple, found several reproachful gazes fixed on her. She quickly covered her mouth, a hurt look on her face.

Yan Feifan already held a special place in their hearts.

While they treated him like a little brother, a relative, and a friend in daily life, they couldn’t help but give him their full, undivided support the moment he got serious about his work.

Yan Ziruo, Shu Lei, Song Yi, and the others instinctively kept quiet, not wanting to disturb Yan Feifan’s experiment.

After four or five minutes, during which Yan Feifan switched the melody twice, his expression began to change.

"I found it! It’s the high-frequency sound that’s doing it!"

Yan Feifan exclaimed, his face lit with excitement, "Playing this high frequency with different melodies... both made me feel distinctly drowsy."

He glanced at the others with a look of regret. "It’s just a shame this sound doesn’t work on any of you. Otherwise, we could run another test to confirm."

"Let me find Mr. Wang..."

Yan Feifan picked up his phone, tapped it a few times, and put it down again.

"Never mind. It can wait."

He turned to Song Yi, his voice filled with excitement. "Song Yi, this high-frequency sound affects both me and Mr. Wang. My analysis is that it’s able to significantly impact the part of our brainstems that controls sleep, either through resonance or some other mechanism."

"The reason you aren’t affected is probably because the frequency isn’t causing resonance."

"However, I believe that the high frequency that *can* affect you should also be near this one."

"We should be able to find the specific frequency that affects each of you through experiments."

Song Yi mused, "So, you’re saying that every person has a corresponding frequency that can be used to induce sleep?"

"In theory, yes!" Yan Feifan replied cautiously.

Song Yi’s eyes lit up. "If that’s the case, we could set up a specialized testing lab! We could find the right stimulus frequency for people with sleep disorders and help them improve their sleep..."

At this moment, Song Yi’s mind was racing.

"The testing could be free, but we’d charge for the player that comes loaded with their specific audio file..."

"We can’t call it a ’player.’ We’ll call it a ’High-Tech Sleep Enhancement Device.’"

Yan Feifan corrected her, "Its effect is more like a sleeping pill."

"It only promotes sleep. Whether long-term use can improve sleep still needs to be studied..."

Song Yi declared, "Then we’ll call it a Sleep Promotion Device!"

"Besides, with this audio stimulation, they can sleep well and soundly without taking medicine. After a while, their physical and mental state will improve, and their sleep will naturally get better."

"Feifan, the company will provide the R&D funds for this project."

"How much do you need?"

Just then, Yan Feifan’s phone rang.

It was a call from Mrs. Yu.

"Feifan, the little girl... we managed to save her life..."

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