Harvesting the second- screen—primarily smartphones but also tablets—is an oasis that many broadcasters have been chasing without success for years, since becoming aware of the now obvious trend of eyeballs drifting from TV screen to palm of hand. QR codes are too awkward. Email campaigns too draconian. Push notifications too intrusive. So what next? What about inaudible ultrasonic sound waves that encode data in audio streams using microsignaling technology? This is the pitch of Texas-based start-up Audazzio, which emerged in 2021 with $1.4 million funding from the Comcast NBCUniversal SportsTech Accelerator Program, when the start-up was then doing business under the name of Sports Sonar. The company’s proposal is to use inaudible signals to synchronize an end user’s device to…