Want Grandpa to stop griping about mumblers? Turn off the TV.

“I don’t need a hearing aid. Just speak clearly!”

Most of us have heard some version of it, usually but not necessarily from an older relative who just asked us to repeat something that they didn’t quite parse the first time. According to research from Johns Hopkins Medicine, at least the first half of that statement is correct: A hearing aid would only make things worse. We often assume that age-related hearing loss, or presbycusis, develops because the ears have grown less sensitive, but findings published December 7 in the Journal of Neuroscience suggest that the opposite may be true.

In a study performed on live mice, researchers found that the brains of older individuals had a much harder time turning off brain cells that fired in response to ambient sound—background noise.

In plain terms, our brains usually filter out sounds that we subconsciously recognize as unimportant: the hum of an air conditioner, the decrescendo of love-hungry cicadas, Auntie Janet talking about her trip to Palmyra. Important sounds are not filtered out. This is why you can carry on a conversation when the water cooler is bubbling full-blast but not when more than one person is talking at once.

To extrapolate these findings to humans, our hypothetical old-timer is half right: They don’t need a hearing aid. A hearing aid that amplifies sound indiscrimately would only turn up the volume on the problem. Because older people know, perhaps from a Christmas whisper shared in a hallway that very morning, that they can hear and parse quiet speech some of the time, they assume that there is nothing whatsoever wrong with their hearing.

So when Great Aunt Bette tells you to quit mumbling you mumbling mumbler why in her day people spoke with respect, beckon her into a quieter area and tell her your story again. And get her some noise-excluding headphones.

Read the abstract in the Journal of Neuroscience.

Shilling-Scrivo K, Mittelstadt J, Kanold PO. Decreased modulation of population correlations in auditory cortex is associated with decreased auditory detection performance in old mice. J. Neurosci. December 7, 2022, 42 (49) 9278-9292. https://doi.org/10.1523/JNEUROSCI.0955-22.2022