When I think of 2012, I will think of the overworked fan of my laptop and the ding of getting a text message on my iPhone. I will think of the beep of the FastTrak in my car as it debits my credit card so I can pass through a toll onto the Golden Gate Bridge. I will think of Siri's uncanny valley voice.

But to me, all of those sounds -- as symbols of the era in which I've come up -- remain secondary to the hissing and crackling of the modem handshake. I first heard that sound as a nine-year-old. To this day, I can't remember how I figured out how to dial the modem of our old Zenith. Even more mysterious is how I found the BBS number to call or even knew what a BBS was. But I did. BBS were dial-in communities, kind of like a local AOL. You could post messages and play games, even chat with people on the bigger BBSs. It was personal: sometimes, you'd be the only person connected to that community. Other times, there'd be one other person, who was almost definitely within your local prefix.

When we moved to Ridgefield, which sits outside Portland, Oregon, I had a summer with no friends and no school: The telephone wire became a lifeline. I discovered Country Computing, a BBS I've eulogized before, located in a town a few miles from mine. The rural Washington BBS world was weird and fun, filled with old ham-radio operators and computer nerds. After my parents' closed up shop for the work day, their "fax line" became my modem line, and I called across the I-5 to play games and then, slowly, to participate in the nascent community.

In the beginning of those sessions, there was the sound, and the sound was data.

Fascinatingly, there's no good guide to the what the beeps and hisses represent that I could find on the Internet. For one, few people care about the technical details of 1997's hottest 56k modems. And for another, whatever good information exists out there predates the popular explosion of the web and the all-knowing Google.

So, I asked on Twitter and was rewarded with an accessible and elegant explanation from another user whose nom-de-plume is Miso Susanowa. (Susanowa used to run a BBS.) I transformed it into the annotated graphic below, which explains the modem sound part-by-part. (You can click it to make it bigger.)



This is a choreographed sequence that allowed these digital devices to piggyback on an analog telephone network. "A phone line carries only the small range of frequencies in which most human conversation takes place: about 300 to 3,300 hertz," Glenn Fleishman explained in the Times back in 1998. "The modem works within these limits in creating sound waves to carry data across phone lines." What you're hearing is the way 20th century technology tunneled through a 19th century network; what you're hearing is how a network designed to send the noises made by your muscles as they pushed around air came to transmit anything, or the almost-anything that can be coded in 0s and 1s.

