Enrico Barausse

An orchestra of millions of instruments plays a single note, but each enters at its own moment and with its own volume. That's how the stochastic gravitational wave background sounds — a hum from black hole mergers that are individually indistinguishable.

A black hole can be compared to a bell: after being struck, it vibrates, emitting a decaying 'ring.' This ring is the gravitational waves that detectors on Earth pick up.