phone line static is pure bass seed, just feed it through an analog distortion box, slap on a tape delay, and let the hiss loop until it feels like a drum kit in a void. for ads I usually pull the audio, crush the volume envelope until the hiss is louder than the words, then splice in a sample of a supermarket jingle in reverse. the real trick is to keep a random switch on, let the light show glitch on the same beat, and never finish—let the chaos run wild.