Moreover, the sound is more than ten times louder than listening against the iron frame, and it is extremely clear.

Feeling this magic, Chen Xiang was extremely pleasantly surprised.

"Lu Fei, how do you know so much?" Chen Xiang asked with admiration.

"Hey, your man is the best."

Chen Xiang rolled his eyes and said.

"Can you speak well?"

"Actually this

It’s nothing, this method of collecting sounds was invented as early as the Jin Dynasty.”

"In ancient times, when attacking a city, there were often serious casualties, so Cao Cao thought of a way to have his troops dig tunnels into the city from underground."

"What does Dizijun mean?" Chen Xiang asked.

"Grave robber!"

"puff"

"Don't interrupt!"

"Cao Cao's method worked wonders, but it was quickly mastered by others and used against Cao Cao."

"It made Cao Cao regret it but he didn't have a good defense method."

"Later, Du Yu, a famous military strategist in the Western Jin Dynasty, accidentally discovered that the bucket had the function of silencing sounds."

"After trial and error, it was finally applied in actual combat."

"At the beginning of the sixth year of Taishi, Du Yu was responsible for guarding Longyou Pass."

"In the same year, the Xianbei people's Bald Haired Tree Function rebelled with great force, and their strength was several times greater than that of the defenders."

"The Bald Tree was able to attack the city for three days and suffered heavy losses, but it still couldn't break the city."

"In the following days, the Bald Tree function was still able to attack the city, but the troops invested were much weaker."

"We often feign attacks a few times, and then withdraw our troops and confront them if they don't work."

"Du Yu felt something was wrong, so he ordered a dozen large wooden barrels to be dug out, and they dug a hole in the bottom of the barrel and buried it halfway into the ground. Sure enough, he found the sound of digging in the ground."

"Du Yu asked the soldiers to follow the sound."

"When the enemy breaks out of the ground, stay up there and wait for work to defeat the enemy."

"Since then, this method has been widely used."

"In the Sui and Tang Dynasties, wooden barrels were replaced by pottery jars, and the effect was much better than the former."

"By the Ming Dynasty, a ten-meter-long vat had become a must-have standard within the walls of all cities."

"The conductivity of metal is much better than that of ceramics."

"In the late Qing Dynasty, merchant ships and warships were connected by an iron pipe up and down, which was used to transmit sound."
Chapter completed!