Advanced Linux Sound Architecture (known by the acronym ALSA) is a Linux kernel component intended to replace the original Open Sound System (OSS) for providing device drivers for sound cards.
For more information on ALSA, visit https://en.wikipedia.org/wiki/Advanced_Linux_Sound_Architecture.
If you get the following error while building Firefox on Linux, it means a few library files required for ogg or wave support are missing.
checking for snd_pcm_open in -lasound... no configure: error: Ogg or Wave support on Linux requires the alsa library
You can append the following lines to your .mozconfig:
ac_add_options --disable-ogg ac_add_options --disable-wave
If you want OGG support install alsa development library.
sudo apt-get install libasound2-dev