The next day.

"Master, are you going to sea to watch whales again?"

Early in the morning, Wang Qian saw Zhang Zi'an carrying the heavy battery and walking towards Wuling Shenguang, so he guessed his intentions.

"Well, that's right. Zhang Zi'an nodded, opened the compartment door, connected the battery to the motor, and confirmed that the power was fully charged.

"Uh......"

Wang Qian wondered in his heart, although whale watching is elegant, but once in a while is enough, why do you have to go every day? Whale watching is really so interesting? It's not about looking at beautiful women......

"What is this?" he picked up a long rod-shaped gray object in the car and fiddled with it, he hadn't seen it in it before, it must have just been put in.

The surface of the long stick-shaped object is rough, and it feels like the pickup part of a microphone in a KTV, with a long gray wire coiled behind it, and the surface of the wire is covered with plastic.

"This is for underwater recording. Zhang Zi'an was afraid that he would carelessly break the precision instrument, so he snatched it from his hand and put it back in the carriage, "You look at the store, I'll go back - if you don't come back, remember to call the police!"

Wang Gan looked constipated and watched Zhang Zi'an drive away.

Li Kun walked out from next door, approached and said, "Senior brother, Shizun has been driving frequently recently, we haven't touched the steering wheel for a long time, and our hands are all raised...... By the way, what are you doing again?"

"I claim to be recording the underwater voice, but I see that Shizun's demeanor seems to be deceitful, and I suspect that he is perfunctory to me, hiding some secrets and not wanting to tell us......" Wang Qian frowned and pondered, his expression serious.

"Oh, what secret?" Li Kun perked up, and asked nervously, "Is it the correct way to interpret that high-level beast control technique?"

"That's not it...... I see that the things that the master is carrying in the carriage are thick and long, and they look very high-end, probably ...... The legendary uranium rod!" Wang Qianxuan said with a matter-of-fact gesture.

"Uranium rods?" Li Kun was stunned, "What is the master going to do when he got the uranium rods?"

Wang Gan saw that there was no one left and right, and said in a low voice: "Maybe the master secretly keeps a Godzilla ...... in the sea."

"Godzilla? Are you sure you secretly raised a rotten kun?"

"Quack! What did you just say?"

Richard fluttered his wings and flew over, inexplicably excited, just because it heard Y as R......

Zhang Zi'an was very careful when driving today, especially after coming to the beach, slowing down to avoid breaking the valuable equipment in the car.

The underwater pickup that Professor Wei Kang borrowed from him was not an ordinary product, but a high-end product used in the School of Underwater Acoustic Engineering of Binhai University for serious scientific research.

Underwater pickups are not just as simple as recording underwater sounds, if that is the case, you can buy them on Taobao, but a complete set of equipment including signal processing systems. It converts the underwater acoustic signal into an optical signal, conducts it into the system through optical fibers, and then modulates and enhances it, outputs a sound wave diagram, and converts the inaudible sound into something that can be heard by the human ear for researchers to analyze. This system is very valuable, and ordinary people can't buy it if they want to.

Just like yesterday, Zhang Zi'an inflated the assault boat, and by the way checked whether there was any air leakage.

The inspection was fine, and he carefully moved the equipment inside the boat and pushed the boat into the sea.

With heavy equipment ballast, the waterline of the assault boat is deeper than yesterday, and the driving stability is a little higher. He was glad he hadn't bought a storm boat that was too small, otherwise it would have been too cramped right now.

Judging the distance with the naked eye, he stopped the boat closer to the shoreline than yesterday, picked up the gray rod-shaped underwater pickup, and instead of throwing it directly into the water, he first soaked the surface evenly to make sure that no air bubbles were attached to the surface so as not to cause sound distortion, and then slowly released the fiber optic cable.

The fiber optic line is marked with a scale, Zhang Zi'an doesn't know how deep the sea water under his feet is at this time, and he temporarily released 50 meters, and it is estimated that it may be almost to the end - if it is too shallow, all he will collect is the noise of the water surface.

When he was ready, he couldn't wait to put on his matching headphones.

It is truly a high-end professional ear, with a thick sponge that fits the contours of the ear tightly, and after a little adjustment, it almost completely isolates all sound from the outside world.

He flipped the switch, and a real-time waveform of the sound popped up on the small monitor.

After the sound of the bottom of the sea was enhanced, the moment it came into his ears from the earphones, he suddenly felt creepy, and his body shrunk tightly as if he was wrapped in a cold current, and shivered excitedly!

It is difficult to describe exactly what he heard, it was like standing in front of an incomparably thick and vast stone door, watching the stone door slowly open, and countless angelic choirs poured out of the stone door, singing magnificent hymns in unison.

His legs trembled, and if he hadn't been sitting on a rickety boat, he might have knelt down on the spot.

Professional-grade underwater pickups and monitor-grade headphones bring into his eardrums everything from the ocean floor within a kilometre radius, from animals, from ocean currents, from propellers and motors, to distant storms and lightning and thunder – from high-energy storms that can even travel thousands of kilometers across oceans...... In addition, there may be the sound of a submarine that is hidden, but it is limited by the processing power of the human brain, and these sounds are all mixed together, echoing in his mind like a morning bell and a dusk drum.

Occasionally, there would be a few strange murmurs in the majestic hymn, sharp as a howl, or low as a cry, and no one knew what the murmur was, perhaps just the meeting of two currents of different temperatures and densities, or the slight movement of the earth's crust at the bottom of the sea—but these were all speculations, and no one could say what they were.

Animal sounds are the most insignificant of them, muffled by other sounds, and often only discernible when they are very close. Most sea creatures don't chirp, and animal sounds, such as whales and dolphins, dominate.

Zhang Zi'an flicked the lever on the instrument in the direction of the low frequency to enhance the sensitivity of the low frequency, filtering out the high-frequency ultrasound from dolphins, toothed whales, and storms, and focusing on listening to the language communication from the low frequency.

As he moved, the voice in the headphones changed again, and the whole became quiet, changing from a grand chant to a rhythmic breath.

Knock knock......

A series of rapid drum beats, which sound at a rate of about two or three times per second, sound like a pop from a shoddy trumpet, sometimes loud and sometimes low — suggesting that one or more minke whales are wandering in the nearby waters.