Additive Synthesis
Example: A Square Wave (no additive synthesis)
instr 1 ; in orchestra ; p3 = duration, p4 = amplitude, p5 = pitch k1 linen p4, p3/8, p3, p3/3 a1 oscil k1, p5, 1 out a1 endin f1 0 1024 10 1 0 0.33 0 0.2 ; in score
Additive Synthesis Model
Series of oscillators at separate amplitudes and frequencies
Output is sum of individual oscillator outputs
Square Waveform Using Additive Synthesis
instr 1 ; in orchestra ; p3 = duration, p4 = amplitude, p5 = pitch ; all harmonics use same amp envelope k1 linen p4, p3/8, p3, p3/3 a1 oscil k1, p5, 1 a2 oscil 0.33*k1, 3*p5, 1 a3 oscil 0.2*k1, 5*p5, 1 a4 = a1 + a2 + a3 out a4 endin f1 0 1024 10 1 ; in score
Square Wave (additive synthesis with amplitude change)
instr 1 ; in orchestra ; p3 = duration, p4 = amplitude, p5 = pitch ; all harmonics use diff amp envelope k1 linen p4, p3/8, p3, p3/3 k2 linen 0.33*p4, p3, p3, 0 k3 linen 0.2*p4, 0, p3, p3/2 a1 oscil k1, p5, 1 a2 oscil 0.33*k1, 3*p5, 1 a3 oscil 0.2*k1, 5*p5, 1 a4 = a1 + a2 + a3 out a4 endin f1 0 1024 10 1 ; in score
Square Wave (additive synthesis with amplitude and frequency change)
instr 1 ; in orchestra ; p3 = duration, p4 = amplitude, p5 = pitch ; all harmonics use same freq envelope k1 linen p4, p3/8, p3, p3/3 k2 linen 0.33*p4, p3, p3, 0 k3 linen 0.2*p4, 0, p3, p3/2 a5 expon p5, p3, 2*p5 a1 oscil k1, a5, 1 a2 oscil 0.33*k1, 3*a5, 1 a3 oscil 0.2*k1, 5*a5, 1 a4 = a1 + a2 + a3 out a4 endin f1 0 1024 10 1 ; in score
Trumpet Tone Graph (HANDOUT)
String Instruments
Examples: acoustic guitar, violin, cello
The initial portion of a note often has harmonic instability or the presence of audible high overtones.
As the vibration of the string has stabilized, the harmonic content of the sound stabilizes also
Brass Instruments
Examples: trumpet, trombone, French horn
Initial "spit" as the player begins to blow into the instrument
Generally exhibit timbral instability as the standing wave begins to build up in the instrument
Woodwind Instruments
Examples: clarinet, oboe, saxophone
Generally harmonically-rich sounds come from these instruments
The harmonic spectrum deviates little throughout the duration of the note
Keyboard Instruments
Examples: grand piano, Fender-Rhodes electric piano, harpsichord
Traditional instruments contain a significant degree of harmonic instability as the sound progresses
Modern electronic instruments have simpler harmonic structure
Percussive Instruments
Examples: marimba, vibraphone, snare drum
Generally have a rapid increase in the fundamental harmonic(s)
The fundamental frequency remains strongest throughout the duration of the sound
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