Microphone not recognized under Linux.

For several weeks I have been able to use Rocket Italian running under Debian Linux Chrome. Suddenly, Rocket running in Chrome browser stopped hearing my microphone, despite my having told it to recognize https://members.rocketlanguages.com. Debian itself uses Pulseaudio, which does recognize the audio from my microphone, as it always has. I prefer using Linux to Windows, but I need the microphone and voice recognition. If I use Firefox with Debian, my voice is recorded, but, of course, there is no voice recognition feedback.