Vocal cords are like two thin rubber bands with width, which are elastic. When it is necessary to emit bass through the vibration of the rubber band, the rubber band is in a relaxed state, and when the vibration frequency is slow, it emits bass. When you want to sing high notes, the vocal cords need to be tightened, so that the sound will shrink very little, so that the local vibration frequency will become very fast and the sound will become thinner to sing high notes.
When the Adam's apple reaches a high pitch, you will see an obvious depression under the Adam's apple and a small ditch about the width of your finger. This shape shows that your voice is elongated and your songs are good.