A doll that records and transmits what it hears is an espionage device, German officials have concluded. “My Friend Cayla” is now banned in Germany, reports Bill Chappell on NPR.  The doll also is vulnerable to hacking, Cayla’s critics charge. The doll isn’t sold in U.S. stores, but is available on Amazon. Linking Cayla to a smart phone app makes the doll interactive. It also means whatever’s said to the doll will be sent to Nuance, a U.S. company that also maintains a voice-