Microphone Signature Tracking of Covid Exposure

Interesting approach,  with approval of the phone owner I assume, they could the release of such 'random tokens', and another phone within some radius, would pick it up.  Producing a map trace of exposure.  To be analyzed on a secure, trusted database.  Assuming that a significant number of people would approve.

Using Your Phone's Microphone to Track Possible Covid-19 Exposure
Ohio State News
Laura Arenschield
June 30, 2020

Researchers at The Ohio State University (OSU) have proposed a Covid-19 tracking system that would rely on signals sent and received from cellphone microphones and speakers. The system would generate random, anonymous IDs for each phone and automatically send ultrasonic signals between the microphones and speakers of phones within a certain radius. A person who has tested positive for Covid-19 would update their anonymous IDs and the timestamp when the IDs were generated in the past two weeks to a central database managed by a trusted health care authority. The data would be used for contact tracing. Said OSU's Dong Xuan, "The phone will periodically generate some kind of sound token and send that token to nearby phones—and the key advantage over other technologies is that the ultrasound could have limited range and will not penetrate obstacles such as walls."... '