A few nights ago, my son and I went for a walk at Dilworth Mountain Park to admire the sunset. At one point, I noticed that he had his hands covering his ears and I asked him why.
“Can’t you hear that?”, he said?
I heard the footsteps of a couple walking along the path, and I heard some traffic noises in the distance, but otherwise it was quiet and peaceful.
He said that the sounds of the bugs (likely Cicada’s) was overpowering and he was astounded that I couldn’t hear any of it. It was so loud for him that he could barely hear anything else.
He recorded part of it on his phone and played it back for me and I could hear the recording, but not the original sounds. It seems that the playback had lowered the frequency just enough to shift it into a range I could hear.
In my case, I’m sure that my more limited audio range is simply due to age. It’s known that we lose frequency range as we get older.
That isn’t the only reason that our hearing can change though. When we are stressed or anxious then we enter a mobility (fight/flight) response and one of the many things that our sympathetic nervous system does, to prepare us for that is that it tunes our inner ear to be more sensitive to low frequency sounds, and less sensitive to higher frequency sounds.
It does this because the sounds of danger tend to be low frequency - the footsteps of a predator as it approaches. High frequency sounds are less interesting in a survival situation and so our inner ear adjusts to ensure we are focused on the riskiest sounds.
As it turns out, this adjustment of the inner ear also makes it harder for us to hear human voices. Just as I couldn’t hear the cicadas, someone who is stressed because their boss just gave them a deadline may not be able to hear the important conversations going on around them.
Effective communication is hard enough, even when the conditions are good. When people are stressed, this becomes even more difficult.