Matthias Mehl (mehl@email.arizona.edu) has developed an Android app that is available here: https://docs.movisens.com/EAR/
The current recommendation for hardware for the EAR is an unlocked Moto G4, Nokia 5, and Nokia 6.1. They vary in price and size, so be sure to do your own testing on one or two devices before buying a whole batch! The app may also work on other Android devices, but be sure to extensively test it before buying more than one. If you find a good one that works reliably, please let Megan Robbins know (meganr@ucr.edu)!
The iEAR app is no longer available on iTunes to use on iPod Touch devices.