Examination of Ultrasound as an alternative to BT Proximity Tracing

In our NGI-funded project with NLnet we took a look at alternatives to BT for COVID19 proximity tracing, specifically near-ultrasound. What we wanted to understand was how practical it would be to use the existing speaker and microphone devices in mobile phone type devices for this function. The short-version is that it is possible, but not really practical. BT probably remains the better option here. Long version here:


Interesting read. You’ve reached a similar conclusion as the Simmel project from Bunnie Studios, also funded by the Next Generation Internet programme. They also produced some hardware designs that used near-ultrasound to do contact tracing. There are some obvious benefits to that approach, which Bluetooth cannot offer. As you write:

“Ultrasound has some nice theoretical advantages, like not working through walls or other barriers that are likely to also be effective barriers against virus transmission. Thus it has the potential to reduce the false-positive rate.”

Both seem quite useful. The main drawback are power consumption, and the directionality of the speakers. With regards to the audible artifacts, of course, an option would be to shift to real ultrasound.

yes, or the artefacts could be solved by just using more appropriate speakers.