Revision:Synthesis

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Synthesis is a combination of physical electronic modules or a digital software program dedicated to producing ‘synthetic’ sound.

Envelope

An envelope is a series of time values working in conjunction with modulation values. It defines how a sound starts, continues and disappears. It is comprised of concepts such as attack and decay, but other sonic distinctions such as transient and sustain may also be applied in some circumstances. Pitch, timbre, and harmonic content can also change over time and in some cases are considered part of the overall envelope making up a sound.

ADSR

ADSR (Attack Decay Sustain Release) are the four parameters found on a basic synthesiser envelope generator. The Attack, Decay, and Release parameters are rate or time controls, whereas Sustain is a level control. When a key is pressed, the envelope generator will begin to rise to its full level at the rate set by the attack parameter, upon reaching peak level it will begin to fall at the rate set by the decay parameter to the level set by the sustain control. The envelope will remain at the sustain level as long as the key is held down. Whenever a key is released, it will return to zero at the rate set by the release parameter.

AHDSFR

AHDSFR (Attack Hold Decay Sustain Fade Release) are the six parameters found on some advanced synthesiser envelope generators. Hold is the amount of time the Attack value is maintained before going to the decay state, while Fade is a parameter that gives you the option to fade the sustain portion of the signal to maximum or minimum level.

Waveform

A waveform is the physical or digital shape of a sound. Most common types are: Sine (pure with no overtones), Triangle (contains odd harmonics in decreasing amplitude), Pulse and Square (waveform where the transition from positive to negative amplitudes and back is very rapid), and Sawtooth (basic waveform that contains all the harmonics in ever decreasing amplitude, which has a distinctive 'buzzing' quality).

Oscillator

An oscillator is a device which produces waveforms and generates a periodic signal of a particular frequency.

Comments

These notes are aimed at students studying GCE Edexcel Music Technology