"micky" wrote in message
...
I have a pair of Bose Hearphones, cheaper than hearing aids.

I only use it at meetings (which I don't go to because of Corona) and to
watch Law & Order on TV (because all the other shows are loud enough but
it's not.)

The device consists of a yoke with the on/off button, two leds, a
charging jack, and the battery, and two earbuds.

Each earbud has 3 microphones, they say**, and when being put in my ears
they sometimes squeal, which the manual says is normal. Feedback, I
guess.

The question is, when both buds are no longer in my ears, the device
waits a while and turns off.

How does it know that the earbuds are no longer in my ears?

I was going to say because it can no longer
shine a light from ear bud to the other...

One obvious approach would
be temperature or capacitance.

**And it can be set to amplify what's in front, what's in front and to
the sides, and sounds from all diretions, so it probably does have 3
mikes per ear.

As good as this might sound, there are one or two other competitors.
Before I bought this I googled but didn't find them. One will play the
last 10 seconds back again, and iirc will play the last 10 seconds at
reduced speed. I'd feel real bad that I didn't get that one, except I
probably wouldn't use those things, at least at a lecture. If I were in
the market, I'd look at the others before buying any of them.