abgate software package provides LV2 noise gate plugin, 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 abgate
abgate is installed in your system.
Make ensure the abgate package were installed using the commands given below,
$ sudo dpkg-query -l | grep abgate *
You will get with abgate package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Sound |
| Package | abgate |
| Version | 1.1.7-2 |
| Description | LV2 noise gate plugin |
| Sub Section | Sound |