As millions adjust to remote work, unwanted background noises—yelling kids, roaring lawn mowers, barking dogs—have become the scourge of online meetings. Think of Krisp as your mute button for all that. The noise-canceling app, which costs $5 a month if you pay annually and is compatible with any videoconferencing software, uses machine learning to differentiate between your voice and background sounds, filtering out unwanted noises so your colleagues only hear you. —Madeleine Carlisle