[Discuss-gnuradio] How to specify Audio Source device_name?

First, I want to thank the group for the wonderful tutorials on GNU Radio Companion.

My problem needs to use an external signal as the Audio Source. GNURadio defaults to using the microphone in the laptop. I added an external USB/audio device to connect the external signal.

After unsuccessfully trying several other ways to run GNUradio, I downloaded ubuntu-14.04.5-desktop-amd64-gnuradio-3.7.10.1.iso and am running it "live" off a USB stick.

When the USB dongle is installed,

`arecord -l`

...

card 1: Device [C-Media USB Audio Device], device 0: USB Audio [USB Audio]

Subdevices: 1/1

Subdevice #0: subdevice #0

Also there is a device /dev/hidraw1.

So the system recognizes the device when it is present.

The documentation for Audio Source says:

The specific audio device to use can be specified as the device_name parameter. Typical choices are:

- pulse, hw:0,0, plughw:0,0, surround51, /dev/dsp

Well, I have tried every variation of the above I and think of. No entry and "pulse" use the internal microphone. Everything else returns:

RuntimeError: audio_alsa_source

I repeated the identical results on a different computer running Debian testing (aka squeeze) and GRC 3.7.10

Google could not find any helpful information for this error message.