"Okay. Turn on the lights. This is what your eyes should be like. As for the ability to observe from a distance, there should be no training, right?"

"No, I've long noticed that I could see something far away." Ye Yue said.

"Very good. Now everyone try their ears, can you hear anything?"

After a while, Xiaolongnu asked first: "Is there any sound? Why can't I hear at all? I only hear your heartbeat and the friction of blood flowing through the blood vessels."

I nodded. "This only means that hearing has improved. The sound of blood flowing is actually very weak. It is already very exaggerated to hear it. But I want you to listen to it. Now you imagine raising your ears upwards, and of course your ears will not actually move. Just think about it."

As I said, Ye Yue suddenly started to scream. "What sound is this? Is it music?"

"This is ultrasound. When you are in the air, you can use it to determine the surrounding obstacles, which is very convenient. You must learn it well, because the sonar in the water is the same principle, and you must master it."

"Well, I can already feel it, very clear." Adina nodded and confirmed.

"Very good. Then now, turn around and think about lowering your ears."

"Wow. What's this sound?" This time Xiaolongnu called out.

"What you hear now is the infrasonic wave. Its frequency is very low, but the sound field energy is very strong. It can be used as a beam energy weapon. Adina, you and Yeyue are equipped with this weapon, right on your forehead."

"On our forehead?" Yeyue touched his forehead. "Nothing?"

"It's not used this way." I explained: "You need to use infrasound to transmit energy to the opposite steel wall first, and then use ultrasound to stimulate those infrasounds to cause irregular overlap. Try it."

Adina took a deep breath and pointed it at the steel wall as the target. She suddenly made a single note like singing, which sounded like a "ah", but the frequency was very complicated. Suddenly, Adina's tone could rise, and then the steel wall in front shattered all over the ground like glass. Adina herself was shocked.

I smiled and patted her. "Yes, that's it. Just now, this is the extreme way to use sound wave weapons. Of course, it's best not to use them, because it's also a huge burden on yourself. In the future, I will teach you how to sing for a long time and then use singing to hypnify a large crowd."
Chapter completed!