I am attaching a mic to my Raspberry Pi 2 Model B (Jessie) and using it for my PocketSphinx implementation.
I see this in the system:
$cat /proc/asound/cards 0 [ALSA ]: bcm2835 - bcm2835 ALSA bcm2835 ALSA 1 [Mic ]: USB-Audio - Samson Meteor Mic Samson Technologies Samson Meteor Mic at usb-3f980000.usb-1.2, full speed
According to PocketSphinx documentation, I need to move the mic to index 0. In Wheezy, you alter the file located at /etc/modprobe.d/alsa-base.conf with the following:
options snd-usb-audio index=0
However, in Jessie, the ALSA configuration system has changed. There is no alsa-base.conf anymore and it is replaced by /usr/share/alsa/alsa.conf.
The format in the new conf file doesn't seem to be compatible with the old format.