It doesn't need a melody or even a single chord.

A great deal has been written about this single chord and its function within the large-scale formal structure of the entire opera.

One single chord of his lamentation can resound for all the world to hear.

In a second condition, single chords were heard at each ear.

Another provided a single major chord, with the instruction "to be held for a long time."

To this day I still don't know a single chord on the guitar.

I The universe seemed to vibrate to a single plangent chord.

After the final note there was a pause, then again a single chord on the piano.

For me a single chord of Beethoven is enough.

But there's no easy way to specify a particular window with just a single chord.