How to test microphone with Audio Linux Sound Architecture - ALSA

Source: http://linuxconfig.org/how-to-test-microphone-with-audio-linux-sound-architecture-alsa

1. List of sound devices

$ cat /proc/asound/cards
 0 [NVidia         ]: HDA-Intel - HDA NVidia
 HDA NVidia at 0xefff0000 irq 20

you may get bunch of devices but we are interested in the one which seems to familiar to you or the one which has IRQ. Another command to use to check which sound devices are recognized by your alsa system is arecord -l:

$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: AD198x Analog 
[AD198x Analog]
 Subdevices: 3/3
 Subdevice #0: subdevice #0
 Subdevice #1: subdevice #1
 Subdevice #2: subdevice #2

2. Test MIC

to test microphone we would used arecord on the command line. This small utility will record sound from your default alsa default sound device. No special arguments as device name are not required since we I have only one sound card.

$ arecord -d 10 /tmp/test-mic.wav

this will record 10 seconds.

3. Play test-mic.wav

Now it is easy to play your wav file with another simple alsa utility a play:

$ aplay /tmp/test-mic.wav

NOTE:
If you have a more sound devices on your system and you need to use the non default sound card you can specify it to arecord with -D option. For example:

$ arecord  hw:1,0 -d 10  /tmp/test-mic.wav

will use second sound card where 1 refers to card and 0 refers to device as returned by arecord -l command. If you want to change your default alsa sound device globally on the system here is a link to unofficial alsa wiki which you might find helpful:
http://alsa.opensrc.org/index.php/FAQ026