Sox

• Play an audio file:

    play filename

• Convert an mp3 to ogg (the output format is autodected using the new file extension):

sox filename newfile.ogg

• Concatenate two or more audio files:

sox filename1.wav filename2.wav filename3.wav file1to3.wav

Advanced usage

• Create spectrogram:

    sox casa.mp3 -n spectrogram

• Tunning spectrogram example params:

    sox casa.mp3 -n spectrogram -Y 130 -l - casa_spec.png

• Reverse sound track:

    sox casa.mp3 reverse asac.mp3

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how to just put all the tracks together in one file

(all files with stereo sound, so two channels) without changing the volume of any of the inputs in the final output.

• will do exactly what you ask (at most risk of clipping).

sox -m -v 1 ...

• will mix to a volume that is roughly as loud as one input file (with a small risk of clipping) – Note: not available before SoX 14.1.0

sox --mix-power ...

• (SoX 14.1.0) normalises the mixed audio to the loudest possible without clipping

sox -m ... norm

• to compress the mix to make it sound louder.

sox -m ... compand ...

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remove background noise and/or silence from audio files (individually, or in batch).

https://gist.github.com/devoncrouse/5534261?permalink_comment_id=2214084

# Create background noise profile from mp3
/usr/bin/sox noise.mp3 -n noiseprof noise.prof

# Remove noise from mp3 using profile
/usr/bin/sox input.mp3 output.mp3 noisered noise.prof 0.21

# Remove silence from mp3
/usr/bin/sox input.mp3 output.mp3 silence -l 1 0.3 5% -1 2.0 5%

# Remove noise and silence in a single command
/usr/bin/sox input.mp3 output.mp3 noisered noise.prof 0.21 silence -l 1 0.3 5% -1 2.0 5%

# Batch process files
/usr/bin/find . -type f -name "*.mp3" -mmin +30 -exec sox -S --multi-threaded -buffer 131072 {} /path/to/output/{} noisered noise.prof 0.21 silence -l 1 0.3 5% -1 2.0 5% \;

# Remove insignificant files
/usr/bin/find . -type f -name "*.mp3" -mmin +30 -size -500k -delete