Batch Processing

Sox works well in shell scripts and pipelines. The examples here assume a POSIX shell (bash, zsh, etc.).

Shell loops

mkdir -p normalized
for f in *.wav; do
    sox "$f" "normalized/$f" norm -3
done

for f in *.wav; do
    out="${f%.wav}_clean.wav"
    sox "$f" "$out" highpass 100 norm -3
done

${f%.wav} strips the .wav suffix.

mkdir -p mp3
for f in *.wav; do
    sox "$f" "mp3/${f%.wav}.mp3"
done

duration=$(soxi -D "$f")
if awk "BEGIN { exit !($duration > 5) }"; then
    sox "$f" trimmed.wav trim 0 5
fi

ls *.wav | xargs -P 4 -I{} sox {} "out/{}" norm -3

Sox exits non-zero on errors. Always check in scripts:

for f in *.wav; do
    sox "$f" "out/$f" norm -3 || echo "Failed: $f" >&2
done

The -p flag emits sox’s internal format on stdout — no need to specify sample rate, bit depth, or encoding on the receiving end:

sox voice.wav -p trim 0 3 | play - reverb 80

This avoids intermediate files in multi-step pipelines.