SoX is a power-packed command-line tool for various types of audio processing. It's very useful as an audio format converter, and it can be used for resampling audio files, converting between endianness, audio encoding and modifying other attributes of common audio file formats.

Its main power, however, is its effect plugins. It can apply various effects to audio in the same way a digital audio workstation does. You can add echoes, filter frequencies, reduce or increase volume, remove noise and do various other advanced digital signal processing on sound samples.

Its companion program, play, can be used to test what a particular audio effect does before copying the output to a file with SoX. But, play does not understand MP3 and Ogg Vorbis files.

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