The word "apodization" literally means "cutting off the foot" but in signal processing & in optics it is a technical term that means adjusting signal using a windowing function so that the resulting adjusted signal shows some favourable properties such as xdB attenuation at a certain frequency, xKHz or xMHz bandwidth, etc.
Apodization has been used in optics long before it became "cool" to use in audio.
here is an interesting paper by Ayre on their use of a minimum phase filter which they have settled now after having used apodization filters in their prev (2nd) generation.
http://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf
it is my understanding that 'minimum phase' & apodization filters are 2 slightly different things - minimum phase filters eliminate pre-ringing (you know what this means now that you've read Ayre's paper) at the cost of different delays at different frequencies. This means that minimum phase filters are NOT linear phase filters i.e. they do introduce phase distortion but the designers argue that the phase distortion is at high freq & is minimal & is often not of any consequence. Apodization filters reduce the amount of pre-ringing & post-ringing but do not eliminate them. This means that apodization filters are linear phase filters i.e. constant group delay or same delay thru the filter for all frequencies.
here is another nice blog post detailing the 5 (digital) filter choices from a Wolfson DAC WM8741: http://hifiduino.blogspot.com/2009/05/wm8741-digital-filters.html
hope that this helps....
Apodization has been used in optics long before it became "cool" to use in audio.
here is an interesting paper by Ayre on their use of a minimum phase filter which they have settled now after having used apodization filters in their prev (2nd) generation.
http://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf
it is my understanding that 'minimum phase' & apodization filters are 2 slightly different things - minimum phase filters eliminate pre-ringing (you know what this means now that you've read Ayre's paper) at the cost of different delays at different frequencies. This means that minimum phase filters are NOT linear phase filters i.e. they do introduce phase distortion but the designers argue that the phase distortion is at high freq & is minimal & is often not of any consequence. Apodization filters reduce the amount of pre-ringing & post-ringing but do not eliminate them. This means that apodization filters are linear phase filters i.e. constant group delay or same delay thru the filter for all frequencies.
here is another nice blog post detailing the 5 (digital) filter choices from a Wolfson DAC WM8741: http://hifiduino.blogspot.com/2009/05/wm8741-digital-filters.html
hope that this helps....