Roland V-Synth Book page 38

Column
Time-variant timbral changes (Envelopes)
Listening to any acoustic instrument, you will often hear changes in brightness
and volume within each note. Synthesizers make use of Envelopes to emulate
these effects.
Pitch Envelope
Especially brass and woodwind
instruments exhibit a rapid pitch
change at the beginning of each note.
The diagram below shows the typical
time-variant pitch change of the
trumpet. Synthesizers make use of Pitch
Envelopes to emulate such effects:
Filter Envelope
Notes played on plucked or hammered instruments such as the guitar, piano or
drums start relatively bright, then become increasingly mellow as the sound
decays. This behaviour can be emulated in synthesizers using the Filter
Envelope:
cutoff
frequency
A d d i n g E x p r e s s i o n t o a S o u n d
Low Frequency Oscillators (LFO)
LFOs can be applied to the three basic elements of a sound (pitch, brightness
and volume) to make sounds less static than they would otherwise be and give
sounds a "human touch". Most modern synthesizer keyboards include wheels or
joysticks as well as aftertouch (pressure on the keyboard) which can be used for
realtime control over LFO modulation depth.
Vibrato
Vibrato is a cyclic modulation of pitch. Vibrato techniques are often used by
singers as well as instrumentalists (e.g. strings or saxophone) for maximum
emotional effect.
pitch
Un d e r s t a n d i n g S o u n d 2
Trumpet, etc.
pitch
Piano, etc.
time
time
Amplifier Envelope
Notes played on plucked or hammered instruments generally decay down to
silence, while on instruments such as organ or violins, they can carry on
indefinitely at the same level. Either of these basic forms can be emulated in
synthesizers using the Amplifier Envelope.
Piano, etc.
time
volume
Organ, etc.
volume
Key-on
Wah
Wah (originally "wah-wah") is a cyclic modulation of brightness. Wah
techniques are often applied by trumpet players (using a cup-mute), blues
harmonica players or electric guitarists (using a wah pedal) to emulate some
typical formants of the human voice.
cutoff
frequency
Trumpet
Tremolo
Tremolo is a cyclic modulation of volume. A speciality of flute and string
players, tremolo is also available in electric pianos and guitar-amplifiers with
built-in tremolo units.
volume
Key-off
bright sound
dark sound
Wah pedal
loud
soft
time
time
time
time