"Fairy, do me a favor!" Mu Heng came to He Wangwei and Su Su's side, and said with a smile.

"As long as you can help, you can just say it." He Wuxian replied with a light smile.

After Mu Heng got the promise, he turned his back, stuffed his finger into his mouth, used it to hide people's eyes, and secretly took out a piece of dark iron from the storage ring.

"Darksteel?" He Wangwu stared at the white metal block in Mu Heng's hand and asked in surprise.

Su Su was also shocked by Mu Heng's sudden move, and stared intently at the Xuantie in his hand.

"Well, I need a fairy to help me refine something!" Mu Heng handed over the Xuantie to He Forget and said.

"But I don't know how to refine weapons!" He forgot to worry that he was a little anxious when he heard this, if Mu Heng couldn't make a new attempt because he couldn't refine the weapon, he would feel like he had missed the opportunity, which made her very uncomfortable.

"You don't need to know how to refine weapons, you just need to use your spiritual power to turn this dark iron into the shape I want." Mu Heng explained very easily.

"Then I'll try, if I can't get it right, I'll have to trouble Su Su you!" He Wuwu no longer had the frustration just now at this time, and unexpectedly winked a playful eye at Su Su.

"Humph!" Su Su just snorted lightly, but he didn't refuse, that is, he basically agreed.

"Panda, what do you want to refine?" He Wangwu looked at the heavy Xuantie, and he didn't have the heart to pay attention to why this demon beast also had the Outer Darkiron that only the human race would pay attention to.

There is also Su Su who has the same idea, and all his thoughts are on Mu Heng's plan to break the sound barrier. Compared to breaking the Tianyin barrier, Mu Heng is not worth being curious about at all with a little dark iron, and it is a big thing.

With the help of the two, Mu Heng was also relieved. Then he described the "tuning fork" commonly used in physics classes in his previous life to the two of them, and he used his hands and mouth to describe it very specifically.

"Susu, help me!" He forgot to listen to Mu Heng's description, it didn't seem to be easy, so he cast a look at Su Su for help.

"Good!" Su Su didn't have the heart to target Mu Heng at this time, he just wanted to know what Mu Heng wanted to do as soon as possible.

It was only a stick of incense, and with the full cooperation of He Wangwu and Su Su, the steel part of a tuning fork about one meter long and as thick as a thumb was completed.

Mu Heng asked Su Su to help get a wooden block as a base to fix the tuning fork. At the same time, give He Wangwu a fist-sized piece of dark iron and let her help refine it into an iron hammer.

"Hey, it's done!" Mu Heng had a tuning fork in his left hand and a hammer in his right hand, smiling like a fool.

"Fatty, you just want to rely on these two gadgets to break the ban of the Heavenly Sound Barrier?" Su Su looked at the mortal thing in Mu Heng's hand without any aura fluctuations, and sneered.

"Who's Fat!!! Mu Heng screamed, but looking at his figure, he was really bloated, and he didn't have the courage to continue.

"Poof!" Su Su saw that Mu Heng's toughness at the beginning had turned into weakness later, and he suddenly felt funny.

This smile is like a spring breeze blowing, adding a touch of spring to this gloomy mixed yuan mountain.

Looking at this smile, Mu Heng's mood also improved, and he said calmly, "I don't know if I can do it, there is no harm in trying!"

"Hmm!" He Wangwei gave Mu Heng a lot of encouragement, although she also felt that Mu Heng was joking. It was impossible for the two mortal objects in his hands to break the prohibition of the heavenly sound barrier, but she was unwilling to discourage Mu Heng's enthusiasm.

Mu Heng could see that neither of them believed that this tuning fork could work, and he didn't bother to defend it, after all, he didn't have much confidence in himself. Looking back, Mu Heng was immersed in the new experiment again.

Place the tuning fork in front of the celestial sound barrier, and then gently tap it with a small hammer to make a crisp sound: "Dang!"

As soon as he heard the sound, Mu Heng put his head into the range of the Heavenly Sound Barrier and let this sound wave attack him.

The dizziness that was still the same as before came, and Mu Heng quickly retracted his head. At this time, there is no need to prolong the time, because you only need to determine whether the frequency of the tuning fork is the same as that of the celestial sound barrier.

The first attempt failed, Mu Heng adjusted the position of the tuning fork a little and continued to try.

Mu Heng now needs to be determined

One of the two parameters is the frequency of the celestial sound barrier, which makes it easy to adjust the frequency of the tuning fork to the same frequency. At this point, Mu Heng planned to clamp a piece of wood between the iron bars on both sides of the tuning fork to control the frequency of the sound produced by the tuning fork.

The second is to ensure that the initial phase of the two sound waves is half a cycle apart. At this point, after determining the frequency, adjust the initial position of the tuning fork to ensure that the initial phase of the sound wave is exactly half a cycle.

It's easy to say, but under the premise that the two parameters can't be quantified, if you want to achieve this effect, you can only rely on luck, keep trying and adjusting, and find the most suitable point.

Subsequently, Mu Heng began a large number of experiments, constantly repeating the movements of probe, hammering, listening, and shrinking his head, tracing the sensitive points and anastomosis of the tuning fork.

After repeating it four or five times, Mu Heng felt that this seemed too accidental, and an aimless attempt would only waste time.

Then I had a brainstorm, and I had a solution. Using the control variable method commonly used in the experiment, the position of the tuning fork was fixed, and the length of the tuning fork was adjusted by using the wooden plug, and the frequency of the tuning fork was preferentially determined.

With a way to improve efficiency, Mu Heng was not willing to delay for a moment, starting from the bottom, moving the wooden cork up little by little, constantly tapping to make a sound, and then determining whether the Tianyin barrier was disturbed.

Mu Heng tried many times, but he never grasped that point. The distance of each movement of the wooden stopper is constantly reduced, in order to refine it to cause a special response of the celestial sound barrier.

Until all the frequency tests that the tuning fork can satisfy, it did not produce the ideal effect of Mu Heng, and then it was determined that this point is not able to make the sound wave of the tuning fork differ from the initial phase of the sound wave of the Tianyin barrier for half a cycle.

Subsequently, after Mu Heng finished testing this point, he continued to change to the next position. In order to be able to conduct the experiment in an orderly manner, Mu Heng drew a line in the white area, divided the white area into a small square grid, and wrote a number.

Later, the test is carried out according to the corresponding position of the grid order, and the suitable position is found so that the initial phase of the two sides is half a cycle apart.

"Susu, can you understand what Panda is trying to do?" He forgot to worry about seeing all Mu Heng's actions, but he couldn't understand the meaning of Mu Heng's actions.

Break the sound barrier of this day, and knock on the dark iron to get it? Who believes when you say it?

"How do I know, pretending to be a ghost, I think he is about to be unable to pretend." Su Su looked like he was watching a good show, waiting for Mu Heng to admit it.

One day, two days.

In the blink of an eye, it was three days after coming to Mixed Yuan Mountain, Su Su and He Wuwu had no patience to continue to watch Mu Heng keep repeating boring movements, but there was no progress and effect.

"Panda, or forget it!" He Wangwu also began to feel that Mu Heng was wasting time, and dissuaded.

"Yes, even if you stop now, I won't laugh at you, after all, it's not easy to pretend to be so patient for so long." Su Su no longer had the previous disdain, but silently admired Mu Heng's perseverance.

If she is asked to do these things, it will be a captivity, no fun at all, and it is estimated that she will not have the stamina to continue after doing it a few times.

"I'll wait another two days and I'll only finish half of the grid, and I think there's still some hope." Mu Heng didn't look back, and continued to bury his head in his own affairs.

"Hey, this guy is pretty stubborn!" Su Su said casually, but did not stop Mu Heng anymore, but looked forward to Mu Heng ending as soon as possible, and there was a faint trace of unrealistic expectations in his heart.

"Huh?" Mu Heng poked his head into the range of the Celestial Sound Barrier, and he was already familiar with the attack power of the Celestial Sound Barrier, and he easily noticed that the strength of the Celestial Sound Barrier had been weakened a little, and he felt a kind of joy to see the moon through the clouds.

If a certain sound wave can be weakened, it means that the frequency of the two should be the same, and the initial phase should be close to half a cycle.

"The frequency is done, as long as you find the right location, you should be fine." Mu Heng muttered to himself, and suddenly his mood improved.

Mu Heng first fixed the wooden stopper on the tuning fork to avoid creep in the process of the tuning fork vibrating. At the same time, the position of the tuning fork base is adjusted very finely.

Continue the experiment.

"Just like that, I was conquered by you—" The dawn of victory was about to shine here, and Mu Heng hummed a song in high spirits.

In units of half a centimeter, the position of the tuning fork is constantly moved each time, repeating the interference of the sensing sound waves.

Once again, I put my head into the sound barrier, and the sound I heard was smaller than before, but there was no noise, which meant that Mu Heng's goal had been achieved.

This time, Mu Heng's head lasted for a long time, and the time before *** dizziness doubled, and before he completely lost his five senses, he dragged his head back, nervous, and he kept panting, but there was an irrepressible smile on his face.

The purpose has been achieved, but there is a huge gap between the energy generated by the tuning fork and the celestial sound barrier, that is, the difference between the wave height of the two sound waves is too large, if you really want to greatly weaken the attack of the sound barrier, you can only increase the amplitude of the tuning fork, that is, you have to hit hard.

"Panda, are you alright?" Although He Wuwu was a little impatient, he still did not ignore Mu Heng's state, and when he saw that he suddenly became strange, he couldn't help but ask.

"It's okay, it's okay!" Mu Heng responded, and then released his spiritual power again, fixing the wooden stopper and the base, so as not to destroy the sensitive points that were not easy to find. Then he secretly said to He Wangwu, "Fairy, do me a favor."

"What are you going to do?" He replied in confusion.

Su Su was also intrigued by Mu Heng's sudden reaction, and followed He Wangwei closer.

Mu Heng wanted He Wangxian to help knock on the tuning fork, but he himself stood on the starting line and saved a short distance from the tuning fork here.

At the same time, I also want to say hello to the two of them, and when I am going to rush into the sound barrier, in case I am stunned again, I have to ask them to rescue me.