All participating smartphones search for nearby devices and tags via Bluetooth, as Google explains. If they recognise connected and registered devices, they send their location to the network.

With millions of iPhones and Macs out in the wild listening for the missing device’s Bluetooth advertisements and relaying their findings to the Cupertino Mothership, it’s a highly effective ...

Your Sony headphones should appear in the Nearby Devices section ... If they don't appear, tap 'Search from Bluetooth ...