Ultrasonic repellents are devices designed to deter pests like mosquitoes and rodents using high-frequency sound waves. These sound waves are typically above the range of human hearing, making them inaudible to people but potentially irritating to certain animals. The idea is that the sound disrupts the pests' communication and navigation, encouraging them to leave the area. These devices are often marketed as a safe and eco-friendly alternative to chemical repellents. They are easy to use, requiring only a power source to operate. However, the effectiveness of ultrasonic repellents can vary, and scientific studies have produced mixed results regarding their ability to repel pests consistently.