Physical Sciences
July 2, 2024

Audible barcodes – a symphony of data

Barcodes and QR codes have become ubiquitous sights in our current information age. However, they have some notable limitations – specifically, the requirement for line of sight, close physical proximity of the reader to the code, and adequate lighting for accurate interpretation. Soorya Annadurai, an independent researcher and software engineer at Microsoft in the USA, has developed a solution for these situations: audible barcodes, or ‘AuraCodes’. Enabling the encoding and decoding of digital information through the medium of sound, AuraCodes may transform how we interact with information and bring a new harmony to the world of technology.

If you take a moment to pause reading this article and instead scan your surroundings, there is a very good chance you’ll spot a barcode. These little black-and-white stamps of visually encoded information are now so ubiquitous that it doesn’t matter where you are or what you are doing, you’ll likely be surrounded by them. Almost every product, physical or digital, is accompanied by its zebra stripes of digital identity. However, this was not always the case.

The first barcode was conceived by Norman Woodland (pictured) and colleague Bernard Silver.
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The first barcode was conceived in the 1950s by Norman Woodland and Bernard Silver. It was originally based on the much older Morse code. Woodland had been working on a system for cataloguing and identifying products in supermarkets. The story goes that one day he was writing the dots and dashes of Morse code in sand on a beach and then had the idea to extend each dot and dash vertically down to produce the familiar thick and thin bars. Interestingly, Woodland and Silver adapted this original design to produce circular barcodes of concentric rings, but this format never gained traction. The first uses of barcodes were by railway companies in the 1960s, and it wasn’t until the 1970s that barcodes made an appearance in supermarkets, with the first product scanned being a pack of Wrigley’s chewing gum in Ohio in 1974.

A new twist on the original barcode idea was the creation of 2D barcodes, also known as matrix codes or ‘QR’ (Quick Response) codes. The popularity of QR codes is due to their fast decoding speed and the fact they can store more data in an equivalent amount of space. The prevalence of cameras on smartphones capable of reading QR codes has led to them becoming as ubiquitous in modern life as the original, one-dimensional barcodes.

Still, both conventional barcodes and matrix codes have some fundamental limitations – specifically, the requirement for line of sight, close physical proximity of the reader to the code, and adequate lighting for accurate interpretation. This is where researcher Soorya Annadurai comes in. He had the idea of converting the data encoded in conventional barcodes into audio frequencies – his resulting ‘AuraCode’ enables the encoding and decoding of digital information through the medium of sound.

Breaking the sound barrier

To understand how AuraCodes work, it is helpful to first examine the various components of barcodes and matrix codes. Conventional barcodes are composed of a left, right, and centre ‘Guard’ and a ‘Checksum’. The Guards are well-defined, standardised patterns that are always present – if the scanner used to read the code does not detect these sequences, it will not be recognised as a valid barcode. The Checksum is not part of the originally encoded data, but instead allows the detector to validate if the code was correctly scanned, using a well-defined mathematical function. Similarly, QR codes are composed of various required patterns such as position markers in the corners, alignment markers to enable accurate interpretation even if the code is physically deformed, as well as version and format information and error correction keys to verify the accuracy of data decoding.

Spectrogram of an AuraCode.

Building on these fundamental principles, an AuraCode is similarly composed of a ‘Left Guard’ (start) and ‘Right Guard’ (end), a section of ‘Error correction code’ (ECC), and the data to be encoded. The binary information to be encoded is converted into well-defined audio frequencies being played for 0.1 seconds, conveying a half-byte of information. This results in an audio signal that can be played by any speaker and detected by any microphone, allowing the detecting algorithm to reconstruct the frequencies of the notes played between the Guard timestamps, and ultimately decoding the contained information.

Harmonising data with sound

AuraCodes thus overcome the limitations of conventional barcodes – they do not require line of sight, close physical proximity, or even adequate lighting. There are many potential use cases for such a technology. Some examples include device pairing, where an audible barcode would streamline the pairing of a Bluetooth speaker with a mobile device, for example, or data broadcasts in public spaces, such as train stations or airports. Any situation where items need to be identified or data conveyed in poor visibility conditions could benefit from this technology.

AuraCodes overcome the limitations of conventional barcodes – they do not require line of sight, close physical proximity, or even adequate lighting.

Of course, the versatility of AuraCodes extends beyond consumer electronics and public information, finding potential applications in fields such as logistics, healthcare, and education, where the seamless exchange of information is paramount. AuraCodes could also be transformative for people with impaired vision, opening up a new interface between the digital world and the medium of sound, and potentially revolutionising how we interact with technology and information in our daily lives.

Components of a barcode.

Annadurai’s AuraCodes are currently in an early proof-of-concept phase, but the researcher is already planning extensions and enhancements to the technology, including data encryption, improved error correction, and encoding efficiency. Data encryption can be applied using industry-standard encryption algorithms such as AES (Advanced Encryption Standard) or RSA (Rivest, Shamir, and Adleman), enabling the transmission of more sensitive and secure information. Variable levels of error correction can be introduced, so that longer messages can have a higher level of data validation and correction, while shorter messages can remain succinct. Intriguingly, to improve encoding efficiency, multiple non-destructive frequencies can be played simultaneously in the same 0.1-second window, effectively producing a chord. Using a chord-based AuraCode would greatly reduce the time required to play the code, enhancing the efficiency of data transmission.

AuraCodes stand at the vanguard of a new frontier in data encoding and transmission, blurring the boundaries between the digital and auditory. The ability to be detected across physical barriers, at a distance from the audio source, and not requiring line of sight or adequate lighting opens up multiple novel applications, pushing the boundaries of what is possible in the digital soundscape. This requires no specialised hardware – only a speaker and a microphone. Soon, it won’t just be the familiar little zebra-print stamps surrounding you but a full symphony of data!

Personal Response

Which industries or activities do you think will be most impacted by AuraCodes?
I think the potential impact scopes are numerous. Imagine a hospital where announcements are not made in one or two languages, but instead using tones that any phone can pick up and translate. Imagine pairing your home theatre speaker system to your television just by plugging in a few wires, and not using a mobile app to scan, authenticate, and pair your devices. Imagine encrypted phone calls that exchange their security keys over a public telephone network using these special tones. Anywhere that short bursts of data need to be sent without prior handshakes (like a WiFi connection) and without line of sight – AuraCodes can be your friend.

Do you foresee any security risks associated with AuraCodes?

Well, AuraCodes are not inherently designed to be secure… just like conventional barcodes are not designed as a security feature. However, the data inside the conventional barcodes and AuraCodes can be encrypted using various algorithms. The question of security risks would lie with the algorithm used, rather than the medium of transmission. In general, when considering security it’s best to assume that anyone can listen or watch the medium of transmission; it’s up to the user to protect the data in that medium. Assume anyone is capturing your WiFi packets; use WPA encryption to protect your data. Assume anyone is watching your instant messaging chats; use end-to-end encryption. Assume anyone is watching which websites you visit; verify SSL encryption is enabled on those websites. Similarly, assume anyone is viewing the barcode or listening to the AuraCode. Encrypt the data accordingly, if security is a concern.

This feature article was created with the approval of the research team featured. This is a collaborative production, supported by those featured to aid free of charge, global distribution.

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