
Photosounder.com - Image-sound editor & synthesizer - wglb
http://photosounder.com/
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anigbrowl
I'm a fan of additive synthesis (the technology in use here) and recommend
this to anyone interested in electronic music/sound design, with two caveats:

a) you are likely to get the most sonically interesting results by taking
recordings of sounds you already like and converting them to image files, then
applying a variety of filters and treatments in photoshop or similar, before
exporting back to Photosounder for rendition as audio...although this is
necessarily a rather slow process. If you like Javascript, you could get into
Processing, and achieve the same effect by sweeping a windowed fast-fourier
transform across your audio sample (or doing a reverse FFT on vertical strips
of an image). The weird digital quality of the sounds generated by a tool like
this stem from harmonic juxtapositions that do not exist in nature (see
below).

b) the big problem with this and all other spectrogram tools I've used over
the years if that they treat the audible frequency spectrum as a flat
geometrical (edit: cartesian, sorry) space. So if you look at a spectrogram of
a sine wave, you'll see a single horizontal line; if you examine a saw wave
(which includes all harmonics) you'll see a group of horizontal lines of
decreasing intensity from bottom to top.

So far so good, because we can learn a lot from that, but an FFT/Spectrogram
obscures the concept of pitch. For example, in conventional western tuning a
440 Hz tone is the note A, while tones of 220 or 880 Hz are the same note
played an octave lower and higher, respectively. Our brains are 'wired' to pay
particular attention to powers of 2; not just in pure tones, but even in
distorted ones. People generally express a liking for the sound of second-
harmonic distortion (at double the fundamental, the typical electric guitar
sound) while exhibiting an intense dislike for third-harmonic distortion (bad
transistor radio). My point here is that the sound spectrum, unlike that of
light, encompasses multiple octaves and psychoacoustic research provides
strong evidence for the idea that the brain evaluates sounds with multiple
frequency components around a pitch spiral rather than a 2d cartesian
space...but although we have the required computer power, there has been
little progress in the development of tools to represent and manipulate sound
this way. It's hard to find any kind of real-time tools that map the results
of an FFT onto a polar coordinate system.

EDIT: there's some information about construction of the polar FFT here, but
it's regrettably beyond my capacity to implement at present:
<http://www.math.umn.edu/~focm/c_/Elad.pdf>

