Ultrasonic pest repellents are devices that emit high-frequency sound waves, typically above the range of human hearing, to deter pests like rats, mice, and insects. These sound waves are believed to disrupt the communication and navigation of these pests, making the environment less hospitable for them. These devices are often marketed as a humane and chemical-free alternative to traditional pest control methods. They are easy to use, simply requiring plugging into an electrical outlet, and are designed to cover a specific area. However, the effectiveness of ultrasonic repellents can vary, and scientific support for their claims is limited.