To any headphone jack, all audio is raw in the sense that it exists as a series of voltages that ultimately began as measurements by some tool, like a microphone or an electric guitar pickup or an EKG. There is no encryption or rights management, no special encoding or secret keys. It’s just data in the shape of the sound itself, as a record of voltages over time. When you play back a sound file, you feed that record of voltages to your headphone jack. It applies those voltages to, say, the coil in your speaker, which then pushes or pulls against a permanent magnet to move the air in the same way it originally moved the microphone whenever the sound was recorded.

Smartphone manufacturers are broadly eliminating headphone jacks going forward, replacing them with wireless headphones or BlueTooth. We’re going to all lose touch with something, and to me it feels like something important.

The series of voltages a headphone jack creates is immediately understandable and usable with the most basic tools. If you coil up some copper, and put a magnet in the middle, and then hook each side of the coil up to your phone’s headphone jack, it would make sounds. They would not be pleasant or loud, but they would be tangible and human-scale and understandable. It’s a part of your phone that can read and produce electrical vibrations.

Without that port, we will forever be beholden to device drivers between our sounds and our speakers. We’ll lose reliable access to an analog voltage we could use to drive any magnetic coil on earth, any pair of headphones. Instead, we’ll have to pay a toll, either through dongles or wireless headphones. It will be the end of a common interface for sound transfer that survived more or less unchanged for a century, the end of plugging your iPod into any stereo bought since WWII.

Entrepreneurs and engineers will lose access to a nearly universal, license-free I/O port. Independent headphone manufacturers will be forced into a dongle-bound second-class citizenry. Companies like Square — which made brilliant use of the headphone/microphone jack to produce credit card readers that are cheap enough to just give away for free — will be hit with extra licensing fees.

Because a voltage is just a voltage. Beyond an input range, nobody can define what you do with it. In the case of the Square magstripe reader, it is powered by the energy generally used to drive speakers (harvesting the energy of a sine wave being played over the headphones), and it transmits data to the microphone input.

There’s also the HiJack project, which makes this whole repurposing process open source and general purpose. They provide circuits that cost less than $3 to build that can harvest 7mW of power from a sound playing out of an iPhone’s headphone jack. Because you have raw access to some hardware that reads and writes voltages, you can layer an API on top of it to do anything you want, and it’s not licensable or limited by outside interests, just some reasonably basic analog electronics.

I don’t know exactly how losing direct access to our signals will harm us, but doesn’t it feel like it’s going to somehow? Like we may get so far removed from how our devices work, by licenses and DRM, dongles and adapters that we no longer even want to understand them? There’s beauty in the transformation of sound waves to electricity through a microphone, and then from electricity back to sound again through a speaker coil. It is pleasant to understand. Compare that to understanding, say, the latest BlueTooth API. One’s an arbitrary and fleeting manmade abstraction, the other a mysterious and dazzlingly convenient property of the natural world.