An ultrasonic pest repeller is an electronic pest control device that emits a high-pitched sound at a frequency that may cause discomfort to, kill, drive away or incapacitate household pests. Ultrasonic pest control solutions market themselves as easier and safer than more hands-on pest repellents and pest control options. The devices typically get plugged into an electrical outlet. However, some devices are battery-operated for easier use in fields, gardens, sheds and other areas that aren't wired for power. When turned on, the machine emits high-pitched sounds or high-frequency vibrations, which are typically imperceptible to human ears, although some individuals with more sensitive hearing may hear them.