Noisli - Noisli is a fantastic background noise and color generator for working and relaxing. Online soothing ambient sounds like White noise, Rain and Coffee Shop.
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
Noizio - Feeling that the noise of the big city is too much for you to bear?
Wolfram Mathematica - Mathematica has characterized the cutting edge in specialized processing—and gave the chief calculation environment to a large number of pioneers, instructors, understudies, and others around the globe.
Rainy Mood - Rainy Mood is the world's most popular rain simulator. Sleep, study, and relax with the sound of rain.
GNU Octave - GNU Octave is a programming language for scientific computing.