[PlanetCCRMA] using webcam video and webcam audio in same command

[Tom Poe]

# cat /proc/asound/cards
 0 [I82801DBICH4   ]: ICH4 - Intel 82801DB-ICH4
                      Intel 82801DB-ICH4 with AD1981B at irq 20
 1 [U0x46d0x990    ]: USB-Audio - USB Device 0x46d:0x990
                      USB Device 0x46d:0x990 at usb-0000:00:1d.7-1, high 
speed

I'm trying to record both video and sound from webcam.  This command 
works for video and microphone, but not webcam audio:
ffmpeg -f video4linux2 -s 320x240 -i /dev/video0 -f oss -ac 2 -i 
/dev/dsp -f mp4 test.mp4

Does anyone know how to substitute usb audio for /dev/dsp?  I found this 
command:
 arecord -D plughw:1,0 -c 1 -f S16_LE --buffer-size=48000 -v | aplay -f 
S16_LE --buffer-size=48000 -v
which records a loop using the audio from the webcam.  Now, if I can 
translate the arecord device setting to the ffmpeg command, I should 
have success.  Any help appreciated.

Tom