Earbuds - the tiny speakers that fit inside your ears - are universally more popular with young listeners than the less stylish headphones, but have been proven by medical research to damage hearing irreparably, and to do so fast.
In the past, it was when you were visiting your elderly relations that you automatically shouted. Now, I do so when addressing children and teenagers who are already - even if not actually wired up at the time that you bellow at them - slightly deaf.
Exposing your ear drums to badly mixed rock music at 110 or 120 decibels is the equivalent of standing near a jet aircraft.
Many young people expose themselves to this level of noise for hours each day. No wonder, when they sit next to you on the bus, they create the infernal nuisance of noise from their earphones. If they turned down the decibels to the level that most of us would consider a normal level for radio or music-listening at home, they would be unable to hear.
It is one more indication of the fragmentation of what has been called our broken society. Cut off from being able to hear one another, we all sit around, locked in our private worlds, deaf to what the person next to us might be saying.
I notice that when I travel on trains, and sit in the 'Quiet Zone', many fellow-passengers believe that they are being quiet because their deaf ears are tuned into these earbuds. You can hear the bass drums and the annoying tsst-tsst-tsst yards away from them, as they sit, rhythmically nodding in their deaf solitude.
Music used to bind us together, whether we liked classical music at concerts, or whether we enjoyed the sort of light pop played on the radio. It still does so to a much greater extent than anything else in our divided society. But the phenomenon of plugging in earbuds removes the social element from musical enjoyment.
There is something bleak about this. Societies are happy when the greater number have mastered social skills, and this must depend upon people learning to appreciate one another.
How can this be done if we are all plugged in to our separate earbuds, shattering what was left of our hearing, and completely insensitive to the nuisance we are creating for the person sitting at our side?