The “envelope” of a particular sound is defined by four distinct qualities: attack, sustain, decay, and release. Within each of these qualities is a spectrum of possibilities, all of which can combine into a seemingly infinite array of sound articulations. While this framework is primarily used to create electronic sounds, the terminology is also useful in describing acoustic sounds.
- The attack refers to the beginning of the sound. Attacks can be hard and percussive, soft or nearly silent (e.g. a sound that fades in), or anywhere in between. The attack spans from the onset of the sound to its “peak” (the point of highest intensity), after which the decay begins. This span often happens quickly, but it can also be stretched over time.
- Decay refers to a rapid decrease in the sound intensity that occurs immediately after the peak of the attack. Sounds created on percussive or plucked instruments (e.g., piano, harp, xylophone, cymbals, gong) feature a natural decay. For wind instruments, the decay of a sound can occur due to the changes in air support or availability.
- Sustain refers to the portion of the sound following the delay. The sustain features a relatively constant intensity and may be characterized by different qualities and effects, such as fluctuations of dynamics/intensity, vibrato, or timbral change. Percussive or plucked instruments do not allow for any sustain, while others (e.g. stringed and electronic instruments) can sustain notes seemingly indefinitely.
- Finally, the release refers to the end of the sound. Releases can range from hard stops to slow fade outs with soft or near-silent endings.
Goal: Develop an understanding of attack and release.
Instructions: Find four single-syllable words that feature different combinations of hard and soft attacks and releases. Experiment with saying the words in different ways by manipulating your performance of each of the four aspects of the sound envelope. Perform your chosen words in different ways for a partner, and ask them to describe the performance decisions that you made. Optionally, try to imitate the envelope of these words on an instrument.
Goal: Develop an understanding of, and sensitivity to, sound envelope.
Instructions: Listen to a recitation of poetry. Focus on one or two words, and describe how the speaker manipulates aspects of the sound envelope and to what effect.
Goal: Describe the envelope of a given sound.
Instructions: Choose a piece from the playlist below and describe the sound envelope of specific notes or instruments in the recording.