Dummy (/dev/null) soundcard

modulename: snd-dummy.ko

configname: CONFIG_SND_DUMMY

Linux Kernel Configuration
└─>Device Drivers
└─>Sound
└─>Advanced Linux Sound Architecture
└─>Generic devices
└─>Dummy (/dev/null) soundcard
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Say Y here to include the dummy driver. This driver does
nothing, but emulates various mixer controls and PCM devices.

You don't need this unless you're testing the hardware support
of programs using the ALSA API.

To compile this driver as a module, choose M here: the module
will be called snd-dummy.

source code: