If you are trying to be more productive and want to achieve more concentration at your work, you may want to give ANoise a try.
ANoise aka Ambient Noise is an utility which plays various noises such as Rains, Fountains, thunderstorms, fire, sea, night etc. This constant and repeating sound helps general users, students to be more productive and concentrate on their work.
ANoise comes with a PPA installation for Ubuntu and integrates itself directly via System tray sound indicator icon with a popup menu. A very lightweight tool (uses only ~132 KiB RAM) loaded with features such as custom noise file integration via home directory ~/.Anoise, offline playback, sleep timer, last remember playback settings.
There are lots of community developed sound files available to choose from according to your test. Installation instruction below.
How to Install
ANoise installation can be done using PPA in Ubuntu 18.04, 18.10 and related derivatives. Run below commands from the terminal to install ANoise.
sudo add-apt-repository ppa:costales/anoise sudo apt-get update sudo apt-get install anoise
After installation, install below two packages for GUI and system tray integration.
Install below GUI for Ubuntu. Below apt link would open software to install the package.
Install below extension for GNOME Shell Integration. Before installing below extension, make sure you enabled GNOME Shell extension in Ubuntu.
Run
After Installation, open ANoise from application search.

In the GUI, you can browse thru the available sounds as per your needs.

You can also change the statup, play timings and download additional sounds from the web via preferences.
