Great American Vowel Shift
It is called the Great American Vowel Shift. Basically our language is evolving at exponential speed. This means that old movies will soon sound "funny" to us. In our new century we will begin to speak with an accent that would now be max foreign to many.
All the time our language is changing, but now, what we see is a dramatic difference in the sound of vowels. This means most words become odd. You have to strain to understand, much like the static on a radio makes you have trouble with a signal full of noise.
There are consequences to workers in an emergency. Orders may not be followed the way they were before the shift due to difficulty in communication. Things are not the same.