Praat

Praat provides you with a huge amount of specialized tools, which you can use to analyze and synthesize speech. With its rich functionality, the application can be invaluable for speech manipulation. Besides the many operations you can perform with it, you can also use it to draw high quality pictures, to illustrate your work in articles or in a theses. The application is available for all major operating system and it is offered as a free and open source solution.

The software displays two windows, one for input and the other for output images. Once you load a voice recording, in the form of an audio file, on the input window, a wide range of options will be made available. Loaded files are displayed in a list and the new options will be displayed next to it, on the right side of the window.

As previously suggested, the application lets you perform numerous operations, from simply playing to modifying a loaded recording. You can have the application draw spectrograms, view pulses, analyze the recording's pitch and intensity and much more.

Furthermore, modifications are not applied directly to an audio file. Regardless if you convert to mono or stereo, filter sounds or perform other actions, the modifications will show up in the same list, beneath the loaded audio file.