I remember back in the late 90s I had a BeBox and there was this cool nodes-and-connections audio program where you could add various effects. My friend mentio

I remember back in the late 90s I had a BeBox and there was this cool nodes-and-connections audio program where you could add various effects. My friend mentioned this delay effect and so we rigged up a graph where one stereo channel was delayed by some number of milliseconds. The effect was pretty uncanny. Wearing headphones, the sound seemed to be coming exclusively from the non-delayed side, until you removed that headphone and the delayed side was clearly still playing.