Tone: An experimental Chrome extension for instant sharing over audio

Sometimes in the course of exploring new ideas, we'll stumble upon a technology application that gets us excited. Tone is a perfect example: it's a Chrome extension that broadcasts the URL of the current tab to any machine within earshot that also has the extension installed. Tone is an experiment that we’ve enjoyed and found useful, and we think you may as well.

As digital devices have multiplied, so has the complexity of coordinating them and moving stuff between them. Tone grew out of the idea that while digital communication methods like email and chat have made it infinitely easier, cheaper, and faster to share things with people across the globe, they've actually made it more complicated to share things with the people standing right next to you. Tone aims to make sharing digital things with nearby people as easy as talking to them.
The first version was built in an afternoon for fun (which resulted in numerous rickrolls), but we increasingly found ourselves using it to share documents with everyone in a meeting quickly, to exchange design files back and forth while collaborating on UI design, and to contribute relevant links without interrupting conversations.

Tone provides an easy-to-understand broadcast mechanism that behaves like the human voice—it doesn't pass through walls like radio or require pairing or addressing. The initial prototype used an efficient audio transmission scheme that sounded terrible, so we played it beyond the range of human hearing. However, because many laptop microphones and nearly all video conferencing systems are optimized for voice, it improved reliability considerably to also include a minimal DTMF-based audible codec. The combination is reliable for short distances in the majority of audio environments even at low volumes, and it even works over Hangouts.

Because it's audio based, Tone behaves like speech in interesting ways. The orientation of laptops relative to each other, the acoustic characteristics of the space, the particular speaker volume and mic sensitivity, and even where you're standing will all affect Tone's reliability. Not every nearby machine will always receive every broadcast, just like not everyone will always hear every word someone says. But resending is painless and debugging generally just requires raising the volume. Many groups at Google have found that the tradeoffs between ease and reliability worthwhile—it is our hope that small teams, students in classrooms, and families with multiple computers will too.

To get started, first install the Tone extension for Chrome. Then simply open a tab with the URL you want to share, make sure your volume is on, and press the Tone button. Your machine will then emit a short sequence of beeps. Nearby machines receive a clickable notification that will open the same tab. Getting everyone on the same page has never been so easy!