If you let out a high-pitched voice suddenly, by accident, the cricothyroid muscle has extended too rapidly and the myotatic reflex has stopped the muscle extending at same time.
This could also hurt your muscles if you let out a high-pitched voice without warming up first. Conversely, if you extend muscles slowly, the golgi tendon organ(inverse myotatic reflex) extends the muscles more.
Therefore, you need to let out your high-pitched voice gradually.
I’ve heard a vocal coach instruct students and say, “If you want to improve your high-pitched voice, you have to let out a high-pitched voice suddenly.” This is obviously wrong. Please be aware of that.
Note1:It takes a long time if you hurt the muscles relating to vocalization to heal and correct themselves. At my voice care clinic, it actually took 2 years to fix an injured cricothyroid muscle before.
Note2:☆ is the injured part in the above figure. The muscle tendon junction is injured more than the middle. Most of the muscles are relevant to moving the cricothyroid articulation.