# Envelopes in PD

Temporal envelopes are an essential building block of sound synthesis algorithms. They are introduced in the Control Section of the CMB content:

The ADSR envelope is the most widely used temporal envelope. The PD help files contain an example, which can serve as a starting point for an ADSR object. It can also be downloaded here: ADSR

Once stored, the object can be used in custom patches to control arbitrary parameters. The following example controls the gain of a sine wave oscillator with an ADSR envelope. The adsr object has six inlets:

• 1: the trigger

• 2: the peak value

• 3: the attack time (ms)

• 4: the decay time (ms)

• 5: the sustain amount (0...100%)

• 6: the release time (ms)

The delay object emulates a 555 ms key press. The only outlet is an audio rate signal with the envelope:

Exercise

Add a second ADSR with individual parameters to control the pitch of the tone.