Signal envelope

The signal envelope is like a big hug that goes around a sound. Sounds are like little waves that go up and down really fast, but if you drew a line that traced the tops and bottoms of all the waves, that line would look like a curve. That curve is the envelope.

Imagine you're at a rock concert, and the lead singer is shouting into the microphone. When she screams, her voice creates a wave that goes up and down really quickly. But the sound guy might want to make her sound more exciting by giving her a big echo. So he takes that envelope - that curve - and makes it bigger. Now, instead of just screaming, the lead singer sounds like she's singing in a giant cave.

The envelope can be used to change the way sounds are processed, like by adding effects or compressing the sound. It's an important tool for sound engineers and musicians who want to create different textures and moods with their music.