what do you call this electronic device that can hear people's conversations?

Kinda confused what you are looking for, and an even bigger question is why? It sounds like you are seeking out the type of equipment a private investigator might use. Maybe a small explanation of what you are actually trying to accomplish might help others give you some sage advice.

 

Are you being a smart guy and talking about a CB?

 

Is it a hearing aid?

 

It is called a CB and they are obsolete.

All truck drivers are now equipped with a surgically implanted device, that replaces the left ear, called a Bluetooth. Why they didn't call it a BlueEar, I don't know.

This new bionic ear allows all truck drivers to communicate with each other instantly, no matter where they are. Plus it gives us X-ray vision.

BTW, I saw you touching yourself in an inappropriate manner in the closet.

The all-seeing, all-knowing...
Barcode

 

This can be blocked by using a highly technical contraption that goes over the head. It also looks amazingly like an upside down spagetti colender with tin foil all over it.

Mark

 

I know what's he's talking about, but can't remember the real name, or the brand name, but most truck stops carry them, since they are very popular with truckers.
Go back to the shop, at the service/parts counter, and tell them you need to buy some 'Dumbo Ears'.




Just remember, it's illegal to drive in some states while wearing these.

 

Priceless, man! I want one. Of course, being a ham and a CBr, I'll have to fit a 19" whip to one ear and a 102" to the other.

Unless the antennas would make me look weird, of course...

-- Handlebar --

p.s. To the OP: if you want to listen to police & fire folks, you're looking for a scanner. If none of these answers have spoken to you (forgive the pun), then modern science has yet to answer your question.

 

Bluetooth stuff:

Bluetooth is an English translation of an ancient Norse King's name. The BT protocol was invented by engineers in one of those north EU countries there where those people were from and named after him.

"Harald "Bluetooth" Gormsson (Old Norse: Haraldr blátǫnn Gormsson, Danish: Harald Blåtand Gormsen) (probably born c. 935) was the son of King Gorm the Old and of Thyra Dannebod. He died in 985 or 986 having ruled as King of Denmark from around 958 and King of Norway for a few years probably around 970."



In the late 1990's to 2000 or so I worked in a laboratory role with BT technology when it was not even released yet. BT uses the same frequency band as wireless ethernet (internet hot spots/wifi) but is 'intelligent' and hops frequencies to avoid interfering. The BT signal is (was?) allowed by its protocol to be much stronger than wireless ethernet.

There were BT "evaluation boards" we made in those days that one could program any way desired.

For a short time a certain lab manager considered it an amusing prank to program a board to transmit at high power on the same channels as the wireless LAN, and then go out among the cubicles to observe the salespeople's reactions to not being able to hit eBay much less do actual work..

Of course they would ask this engineer as he passed by "what he thought was wrong with the internet", and were told to try all kinds of ridiculous and even stupid things to fix it. They obediently did them too (like putting any nearby CDROMs in an anti-static bag because they emit radiation after being read by the laser in the CD drive, etc).

These remedies always worked because he would go back in the lab and shut it down after a few minutes.