The versatility of Bitcoin as a payment mechanism continues to impress me. Released from the shackles of governments and banks, money now has the ability to spread and be shared in ways we have yet to imagine. Here’s an interesting new(ish) one: You can send your Bitcoin transactions via sound waves.

By simply allowing your mobiles microphone to listen to a “chirp”, all the required information for making the payment to the merchant or digital Bitcoin wallet is provided in a mere second or two. The information received in the broadcast would include the payment address, the amount to pay, and the label (Order ID, invoice number, description etc).

Why use sound waves?

Faster than taking a photo – Creates a faster payment then using a camera to scan a QR code. The transaction is instantly picked up by the receiver, and pre-fills in the Bitcoin address, amount and label. (Assuming the wallet has chirp integration)

You don’t have a camera or NFC – Maybe it’s broken, maybe you don’t have one, or maybe you are safety conscious and don’t want your phones camera to be enabled. All working phones have an in-built microphone and speaker.

Chirp In Action

Chirp is a phone application available on iPhone and Android that uses sound to transmit information between devices. Although not Bitcoin integrated, it demonstrates the application of using sound as an information transmission medium. It is designed for quick and easy sharing between people in the same place. A ‘Chirp’ is like a tiny piece of music, and each chirp lasts about two seconds.

“The system listens out for a couple of dozen notes played rapidly in a certain order, within a certain range, at a certain speed. The audio engine tries to decode the sequence of notes into a sequence of letters which our server understands. The server then returns a link to the user so they can go wherever the short code points: to a webpage, say. This decode all happens in real-time on your phone.”

There are some possible issues using sound as the exchange medium– In a noisy environment, it may be hard for the microphone to discern the message, or ‘chirp’ from the background noise, i.e. in a noisy night club. Additionally, malware could be used on a device to change the receiver address without the sender’s knowledge.


While not the most applicable transaction medium for all Bitcoin payments and exchanges, using sound waves to perform transactions between two parties demonstrates Bitcoin’s versatility as a payment mechanism. In a recent talk, Bitcoin expert Andreas Antonopoulos touched on the idea that money is now a content type, providing interesting ways in which Bitcoin transactions could be embedded in other data types. Essentially, Bitcoin transactions can be stored in any information medium without giving away any sensitive information, for example: Hue variations in a photo’s red coloration, hidden in an eBook, or a string of emoticons in Skype. This demonstrates the stark contrast between credit card payments, whereby you summon all sensitive credit card and personal information to a company, and then that company stores this information in a centralised server ripe for hacking. For example: Sony, Bebe Clothing, Target, HSBC.

It will be interesting to see if any Bitcoin POS (Point Of Sale) systems or digital wallet applications introduce a chirp like mechanism to receive/send payment via sound waves in the near future. It is a novel approach that bears several advantages, while being pretty cool at the same time.

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