alsa-base software package provides dummy package to ease purging of obsolete conffiles, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install alsa-base
alsa-base is installed in your system.
Make ensure the alsa-base package were installed using the commands given below,
$ sudo dpkg-query -l | grep alsa-base *
You will get with alsa-base package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Sound |
| Package | alsa-base |
| Version | 1.0.27+1 |
| Description | dummy package to ease purging of obsolete conffiles |
| Sub Section | Sound |