I refuse the ending!

With all due respect to the OP - the movie audience only really were exposed to the family and the environs surrounding them. We had no idea what was really happening in the rest of the world. For all we know, the world's best minds had figured it out.
We were only privy to the family's plight. That was not a plot hole.

Also in answer to the other posters comments:

"The monsters seemed pretty easy to kill..." No they weren't. they were heavily armored, with the exception of their auditory area. That is were the Mom shot the creature in the end.

"and how did they print the newspapers telling people to be quiet, I’m pretty sure printing presses make a lot of noise" - Old fashioned printing presses do make a lot of noise, but the newer ones are lot quieter. Not silent, but quieter. I have worked in a printing shop. Also, most printing shops are in concrete and brick buildings. That material dampens sound very well. When the presses were running in the last shop I worked in, you could not hear them outside the building.

Make of my comments what you will. Just my two cents.

Hi,

It isn't a plot hole because no one knows what occurred before the action in this film. It starts off with an isolated family walking down a road, no one is around. They are on their own. We have no idea what transpired to get to this point, other than it was a world-wide event as per the newspaper accounts. What if there were other aliens not shown in the movie with different features? For instance, they sent down their invasion force made up of invincible aliens to wipe out the world's armies. Once that was accomplished, they let loose the blind monsters to track down the survivors with the eventual goal of inhabiting the planet. At that point, the remaining people had figured out that the monsters were attracted to sound, but by then millions of them were loose and no further information was to be had. The survivors would therefore have no idea how to deal with the subsequent wave unless they figured it out for themselves. They only knew to be quiet. In this case, one parent's attempt to create a working hearing aid for his kid accidentally created a frequency the monsters were susceptible to. It was pretty clear that they had lava-like heads which when closed, were likely impervious to bullets. It was only when the high-pitched sound opened their heads that the shotgun was effective.

So maybe the best minds simply didn't have a chance to figure anything out, they were the first to go.

Yeah, there's quite a bit of dumb stuff in this movie.

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