Two folk poets sang the way.. ..but couldn't hear what they had to say

You see me in horror movies, You see me before blackout, I am light's hiccup, I warn you.

If a deep secret is brought to the surface, the one who revealed it blows this on purpose. It’s the very last sign a conductor will make, a sound you must hear for your journey's sake.

I’m shared in whispers, soft and low, with only those you trust to know. I’m safe when kept behind closed lips, but one loose tongue and off I slip.

This four letter word for a thick mist, often chemical and usually considered toxic or harmful at least, is a portmanteau of smoke and fog