Audible or Inaudible Ultrasound? Advantages and limitations of each

At the core of Chirp is one simple objective — to leverage sound’s unique characteristics and affordances to enable a whole world of machine-to-machine interactions.

By leveraging sound, Chirp technology bridges devices, technologies, and platforms in ways that other technologies simply cannot. Sound is ubiquitous as a medium and billions of devices, both new and old, already have the hardware required to interact and start exchanging data using Chirp.

With sound being such a ubiquitous medium, it is incredibly important for companies providing data-over-sound solutions to provide technology that spans different platforms, architectures and use cases. Chirp technology is available in both audible and inaudible (ultrasound) on iOS, Android, JavaScript, Python, Windows, Linux, Arduino, Raspberry Pi, Smart TV platforms and web browsers. It has been proven and tested in the real world through extensive use and successful implementation on a mass scale in a vast range of sectors including ticketing and transportation, interactive gaming, broadcast, payments, manufacturing and robotics.

When deciding whether an audible or inaudible solution is right for your use case, it is important to understand the unique characteristics of both. Here, we look to summarise the advantages, limitations, and potential use cases of each:

Audible

There are several advantages to using audible sound to transfer data. These include:

• It’s more widely supported than ultrasound. Audible methods of data transfer work across a wider range of devices and media than ultrasound (e.g. AM/FM/DAB radio, many online video streaming sites, telephones, etc).
• It’s able to carry more data. Audible can transmit the greatest amount of data reliably because it uses a wider frequency spectrum than ultrasound.
• It works well in a wide variety of environments. Audible is robust and reliable in the most challenging acoustic environments.
• It is audible. Audible is honest and transparent. The data transfer is heard.

Some typical use cases for audible technology are:

• Embedding into AM/FM/DAB radio broadcast and some online video platforms which strip out ultrasonic frequencies.
• Broadcasting over loudspeakers or PA systems to a fleet of machines or devices.
• Communicating with old, basic or lo-fi audio equipment.
• Scenarios where larger amounts of data must be sent to devices which are offline, such as transmitting video game characters and trading cards.

Inaudible (Ultrasound)

Advantages to using ultrasound to transfer data include:

• It’s inaudible. Ultrasound can be used to silently transfer data from one device to another. This is powerful in situations where users are concerned about noise pollution or where other audio or music is playing.
• It can be used as a ‘beacon’. Unlike audible Chirps which are typically played once, ultrasound Chirps can be played continuously on a loop. This means they can broadcast information to passers-by, effectively acting as an audio ‘beacon’.
• It can be embedded into other media. Because ultrasound uses a different frequency band, it can be played alongside other audio (even from the same loudspeaker) without interference or loss of reliability (this assumes that ultrasonic frequencies are supported by the audio equipment or media player). This means ultrasonic Chirps can be embedded into music, TV programmes, sonic branding, jingles or audio alerts.

Some typical use cases for inaudible technology are:

• Synchronising second-screen applications with TV broadcast in real-time.
• Embedding vouchers and offers into TV ads, which can be received by an app.
• Proximity marketing in retail locations to deliver product information and offers to shoppers.
• Making brand jingles come alive and become interactive.

Please visit Chirp.io to find out more about our data-over-sound solutions or get in touch on contact@chirp.io.