[microsound] palindromic sound

[Kim Cascone <kim@xxxxxxxxxxxxxxxxx>]

> A palindrome
> is a linguistic
> term, and fractal geometries are not described in
> terms of that low
> level of Cartesian symmetry...

let me see if I understand the concept of 'palindromic echo':

direct sound: [ABCDE] is emitted by object
reflected sound: [EDCBA]
essentially 'reversing' the sound
is this correct?

if this is correct then it is basically bovine excrement
there is no process in nature (except human agency) which can 'reverse' 
the order of sound waves post-reflection
analog/nature is basically FIFO, not LIFO
in order for a LIFO condition to occur you have to fill a buffer (which 
takes time) and then spool it out backwards i.e. reverse time
and the forward arrow of time doesn't behave this way

also, even if palindromic echos were true they wouldn't cancel out the 
direct sound
you can try this very easily with a sound editor
open a file containing a dog bark or whatever
apply the process 'reverse' in your favorite sound editor
do a paste mix of this with the original (make sure to scale each by 
50% so you prevent clipping and overload)
listen to result

now the above is a clean laboratory experiment but when you introduce 
all the properties of physical reflection into the equation then you 
are dealing with frequency dependent phase shifts, filtering behaviors 
due to reflecting material, absorption (freq dependent gain changes) 
and a slew of other things that happen to a sound after reflection 
which make it near impossible to use a reflected sound to cancel out a 
direct sound...

any acousticians out there care to comment?


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