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From Earfilter
earfilter.org
Filter your ears!
This site is a wiki for anyone interested in helping create an open, portable, affordable platform for stereo DSP (digital signal processing).
The aim is to create a device that's small and light enough to fit into a handbag, battery powered (or at least easy to power from other convenient sources, such as USB, or cellphone chargers) and yet is capable of running at least a four-band dynamic processor and an eight-band parametric equaliser, at 32-bit resolution, 44.1kHz or higher, on a stereo line-level input, with the output being fed to an onboard headphone amplifier. Input and output connections will be made on 3.5mm jack sockets. It will be possible to switch off the headphone amp (to achieve line-level output) or to adjust its gain (e.g. via a thumbwheel potentiometer if it's analogue, or via buttons if it's digital).
Both the audio filters the device runs and the order in which it runs them should be user-adjustable, even if that requires plugging the device into a PC to make the adjustments. The process of making the adjustments should, however, be at least as easy as setting up a plug-in chain is in Wavelab or any comparable audio editing application.
The initial primary application of the device will be to assist users with damaged frequency-responses to hear music in a balance closer to that enjoyed by people with normal hearing.
Back story
For a little history on earfilter.org, read this.
