To limit the audio file input.wav containing noise mixed with a pure 1000 Hz frequency sinusoidal tone to 995-1005 Hz, using SoX :
sox input.wav output.wav sinc 995-1005
However, the volume changes dramatically as well, which I don't want. It should simply block everything above and below without messing up the rest. The aim is to extract the RMS amplitude of the pure sinus tone from this. I know how to do it in GoldWave, but this program is GUI-only, and thus not practical for many files. What needs to be added to the SoX commandline to get the desired result ? The SoX manual is just gibberish to me (undocumented options, lacks examples).