Skidmore College
Modeling Timbres

Modeling Timbres With FM Synthesis

MAKE AN FM BASSOON

OK, so now you know quite a bit about FM synthesis, but how do you make BESSIE (or any other synthesizer that uses FM) sound like musical instruments you already know and love ? This is what "modeling timbres" is all about.

Near the end of John Chowning's famous article on FM synthesis (see bibliography), he gives a bunch of "recipes" for creating sounds which are more familiar to us (traditional brass, wind and percussion instruments). What follows are variations on some of the parameters from Chowning's listing. If you set BESSIE'S values like these below, you may hear familiar musical instrumental sounds coming from BESSIE.

Try it !

(try to come as close as possible to the following suggested values)
------------------------
Envelope for woodwind-like tones:
(This may sound something like the low register of a Bassoon)

attack=.1 decay= 0 suslevel=1 dur=@1 release= .1

FM Parameters for woodwind-like tones: (Bassoon-like)

Modulation Index = 1*
Modulator Ratio = .2
Frequency Multiplier = 1
Carrier Frequency = @ 300-600Hz

------------------------
Envelope for Percussive tones: (bell-like timbres)

attack=0.04 decay=0.03 suslevel=1 dur=@.1 release=5

FM Parameters for Percussive tones (bell-like timbres)

Modulation Index = 2*
Modulator Ratio = 1.4
Frequency Multiplier = 1
Carrier Frequency = 440-2,000 Hz

-------------------------
Envelope for brass-like tones:

attack=.1 decay=.2 suslevel=.75 dur=.2 release=.1

FM Parameters for brass-like tones:

Modulation Index = 1*
Modulator Ratio = 1
Frequency Multiplier = 1
Carrier Frequency = 440 Hz

*(actually, Chowning suggests that the Index be in direct
proportion with the Amplitude, meaning higher index
values should be used the louder the brass player plays,
but BESSIE 3.0 does not have dynamic Index functions yet)
---------------
New Timbres !

Perhaps the most fun of BESSIE is trying to discover entirely new
sounds !?! Experiment with all the parameters of BESSIE and HAVE FUN, you're likely to hear sounds you've never heard before. In fact, if you really like some of the sounds you create, in future, you will be able to save them by pressing a "SaveSound" button.

Improvise a New Piece of Music with BESSIE !

Since holding down the 'alt' key and then pressing the return key on your keyboad will also play a note on BESSIE, why not create a new piece of music. Create some "long" sounds using the Amplitude Envelope Window and while moving the Carrier Frequency slider, keep hitting the return key.....in no time at all...you'll be improvising your own real-time FM composition !

(who knows, maybe you can even get a grant to study this fun !)

Thanks for using BESSIE !

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