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FS (Formant Shaping) and FM
(Frequency Modulation) Synthesis
FS (Formant Shaping) and
FM (Frequency Modulation) Synthesis
Although based on Yamaha’s newly developed FS (Formant Shaping) synthesis technology, The FS1R actually
integrates two tone generation concepts for extraordinarily broad voicing versatility. Formant Shaping synthesis
gives musicians unprecedented capability to produce and control sounds with characteristics and flexibility similar
to that of the human voice. It can also produce instrument voices that have the response and rich pitch-dependent
timbral variations — in short, the “musicality” — of natural acoustic instruments. The bonus is that the base FS
technology has been realized using an architecture which also lends itself ideally to FM synthesis, similar to the type
introduced in the legendary Yamaha DX-series synthesizers and TX-series tone generators. Thus the FS1R can
create anything from totally new simulations of human vocal sounds to classic DX electric piano voices, and
anything in between.
FS Synthesis
The term “formant” refers to the distinct spectral patterns which define the recognizable sounds of human speech,
such as the vowels “a” or “i.” In human speech, the vocal cords themselves are only capable of creating the basic
driving sound and defining pitch (similar to the oscillator in a music synthesis system). The formants which define
the sounds of speech are created by the shape of the vocal cavity (i.e. the trachea and mouth). In traditional speech
synthesis systems this is simulated by using an oscillator to perform the function of the vocal cords, and a series of
controllable bandpass filters to create the required format shapes. Consonant sounds such as “k” or “t,” and
fricatives such as “f,” are based on slightly different principles, requiring a noise generator rather than an oscillator,
and depending more on amplitude envelope shape than formant shape for recognizability. Formants play an
important role in defining the sound of many acoustic musical instruments as well as the human voice.
Rather than a cumbersome system of oscillators and filters to synthesize the effect of formants, the FS synthesis
system consists of 16 formant “operators” — 8 “voiced” operators, and 8 “unvoiced” operators (3 to 5 formants are
generally considered to be more than enough to synthesize speech). Each operator digitally simulates the effect of
both the driving source (oscillator) and filter in one easily manageable unit. The voiced operators produced pitched
sounds which can be played on a musical scale via a MIDI keyboard or other MIDI controller. The unvoiced
operators can be used to produce noise components of speech-like sound, or they can be used in much the same
way as noise generators in more orthodox synthesis systems (e.g. to produce percussive sounds or sound effects).
The term “operators” is borrowed from Yamaha FM synthesis, because the FS1R’s voiced operators can be
combined in a variety of “algorithms” to create sound in exactly the same way as in the original FM synthesizers
such as the DX7.
1
2
3
4
5
Operators
Voiced
Unvoiced
Formants
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7
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