I know, fun right? How can this help me?
So, dynamic range compression is where you stop amplifying all input levels at the same ratio. If your TV is too quiet for speech, but way too loud when the music or fight scene comes on, you will be interested.
If your TV or sound bar amplifies all sound indiscriminately, quiet sounds are very quiet, and loud sounds are, well, loud.
If you’re hard of hearing, you then turn up the TV volume to hear the speech, and get deafened when the music rises or the adverts come on.
In your audio/sound settings, you can often change this feature. It will be called different things on different systems. You’re looking for something called maybe “equalised volume” or “night mode”, WDRC or DRC even. You don’t want “movie”!
What is now happening is that instead of e.g. doubling quiet, moderate and loud sounds, the TV is e.g. tripling quiet sound, doubling moderate and leaving loud well alone. Dynamic range refers to the gap between the softest and loudest sounds, and this range has now been artificially compressed.
Hearing aids also compress dynamic range, some better than others.
Add to the comments if you need help, or if this helps you.