An electronic repeller is a device that uses ultrasound to deter animals. This is a high-frequency sound that lies outside the range of human hearing. For target animal species such as martens, mice, rats, or certain birds and insects, this sound is very unpleasant and disruptive. The goal of the device is to create such an inhospitable environment for animals in a protected area, for example in a house, garage, vehicle engine compartment, or garden, that they will voluntarily leave it. The repeller does not physically harm the animals; it merely discourages them from entering or staying in the given area.