Hotel kitchen stove gas will make a sound when the firepower is increased. What happened? Turn down the fire and it won't make a sound. Why?

Why is there a round thing on each fuel tank? It's called an air pressure valve. If there is no pneumatic valve, the released gas will have no pressure and the burning fire will have no power. Therefore, as long as you turn on the switch, it will make that sound. When you turn it to a low fire, the air pressure will decrease, and the smaller the switch is turned on, the smaller the sound will be. That's the reason.