I have been shown how to filter a noisy audio track using Audacity. Audacity forum link here Audacity accepts python script commands however not for the crucial noise reduction function. I have looked for a command line tool to do this process and SoX appears to be suitable. The 1st step in Audacity is to apply the following: Effect > Filter Curve > Manage > Factory Presets > Telephone Filter Reading the SoX manual - SoX does not provide a filter curve. SoX does however provide this. equalizer frequency[k] width[q|o|h|k] gain Apply a two-pole peaking equalisation (EQ) filter. With this filter, the signal-level at and around a selected frequency can be increased or decreased, whilst (unlike band-pass and band-reject filters) that at all other frequencies is unchanged. frequency gives the filter's central frequency in Hz, width, the band-width, and gain the required gain or attenuation in dB. Beware of Clipping when using a positive gain. In order to produce complex equalisation curves, this effect can be given several times, each with a different central frequency. Is this the right SoX function to use? How do I use this function to achieve the EQ curve? Regards, Derek Noffke PurpleSwift Cell: 082 780 4680 Tel: 021 761 8264