It’s life threatening when it occurs in a patient during or immediately post heavy sedation or general anaesthesia because the normal nerve-muscle communication is blocked, and is one of the key reasons why we need breathing tubes going through the vocal cords into the trachea when having an operation or when sedated in ICU (I’m an ICU nurse).
Outside that, it’s an experience most people will have during normal everyday life but very rarely. I can still remember the last time it happened to me - I was at work and eating sweet (as usual!) that made my mouth water a lot and a drop of saliva must’ve dropped onto my vocal cords from the back of my mouth. Within ten seconds I was breathing adequately again but my goodness it was utterly terrifying.
I was scared it would happen again last winter when I had three months of one sided numbness in my face, including my mouth, meaning that I kept biting the inside of my cheek and coughing and spluttering every day when eating and drinking. Thankfully I didn’t get another proper laryngospasm again.
What I was trying to say is that it’s a protective reflex that the body does, like a cough or sneeze, but a little more ‘full on’ and deeply unpleasant to experience. But homeostasis is a wonderful thing and the vocal cords’ natural state is to be relaxed and floppy and it is safe to assume they will easily return to that condition quickly after a spasm.