Ok, so let's imagine a scenario where you're living with someone (or maybe staying with someone for the weekend) in a very large house. You want to say something to the other person, but they're on the other side of the house. What do you do? You could yell, of course, but that requires a lot of exertion, and also there's the risk of being misunderstood. Nowadays, you would surely call or text them. In the past — we're talking way back in the '60s, before personal cell phones — there was another option. Some homes, mostly those of very wealthy people, had in-home intercom systems, so you could speak directly to people in other rooms just by pushing a button. Pretty neat.
The '60s and '70s were really the heyday of the home intercom system, though intercoms in the office existed far before then. NuTone, a popular purveyor, introduced its first model in 1954. (The early NuTone intercoms were built with vacuum tubes, a technology you might remember from computer science class.) You might have had an intercom system at home, if you were born at a particular time and in a particular house, in which case you might recall the voice of your mom or dad suddenly blaring over a loudspeaker in your bedroom. Or maybe you have memories of homes with unused or nonfunctional speaker boxes embedded into the wall, the relics of a more (or less) connected time.
Like a lot of weird conveniences (Anybody remember telephones in the bathroom?) home intercom systems eventually lost traction, and then ultimately were replaced by technologies that made their once-remarkable abilities commonplace. Landlines (RIP) typically had an intercom feature, that let you ring other handsets in various room around the house. But in the end, unless you have a very large house, communicating with people in another room is arguably not very hard—and now cell phones make it even easier.
This doesn't mean that you can't still buy a home intercom system. Nutone still makes them, and relatively new to the market is Nucleus, a wireless home intercom. I'm a bit of a Luddite, so I don't have a speaker system or an Amazon Echo, but Apartment Therapy's Lifestyle Editor Taryn, who has multiple Echoes, tells me that you can use them just like you would an intercom. You can use the Announcements feature to broadcast a message to every device on your network, or use the drop-in feature to communicate with just one other room. An exciting (and maybe terrifying) aspect of the drop-in feature is that even people outside your network can use it, if you give them permission. So if, for example, you allow your mom to drop in on your Echo, she can beam her voice directly into your living room whenever she so pleases. Technology is a great way to stay connected! Even, maybe, when you don't want to.
For further reading:
• The Golden Age of the Intercom at Invisible Themepark