Do Electronic Sound Machines Work to Repel Rodents?
Electronic rodent repellents are ultrasonic pest control devices that emit a series of high frequency, short length sound waves designed to drive pests away. It's an environmentally safe option for rodent control that eliminates the mess of having to deal with the bodies of dead animals.
However, the effectiveness of ultrasound as a repellent is controversial.
How it Works
An ultrasonic pest repellent device uses powerful sound waves that cause pain and discomfort to a rodent's ears. The modulated high frequency can induce distress in most animals, which encourages them to leave the area where the sound is coming from. Once the animals are repelled, the manufacturers of these devices claim they won't come back.
When rodents are driven away from their source of food and shelter, they're no longer able to breed, build their nests, or communicate with each other.
The repellent begins taking effect within 2 to 3 weeks, but it can take as long as 4 to 6 weeks before seeing a significant reduction in rodent infestation.
The electronic sound machine, or ultrasonic repellent device, creates a penetrating sonic pulse of 300 hertz (Hz). A human's range of hearing is between 16Hz to 20Hz, and though dogs hear better than people, their range is between 20Hz and 70Hz, so in theory they won't be bothered by the repellent.
Indoor devices plug into wall outlets and may have adjustable settings for frequency and sound-pattern. They work in areas between 500 and 3,500 square feet.
Outdoor battery operated units can be effective up to 10,000 square feet. When stuck in the ground near crops and gardens, the sonic noise is supposed to chase away burrowing rodents.
Humans won't be able to hear the ultrasonic pulses from a device, and pets like dogs and cats are usually not bothered by the noise. However, other pets like rabbits, mice and guinea pigs will likely be affected.
Though the frequencies are inaudible to people, they can be heard by microphones and other electronic devices, and may interrupt clarity of sound when talking on the phone. It's also possible for these devices to cause muting in hearing aides. Signals from burglar alarm systems could be disrupted as well.
The Federal Trade Commission is dubious about the effectiveness of these gadgets as they are not guaranteed and don't always work. Other alternatives to controlling rodent pests without traps and chemical pesticides is to prevent rodent infestation by sealing cracks outside the home, and to eliminate any weedy growth near the house where they often hide.
Animals can grow accustomed to an ultrasound device in a short amount of time. If the food and shelter that lured them in the first place is still available, the rodents will return. A benefit of these devices is that they can increase the effectiveness of trapping by changing the movement patterns of rodents so they can be herded into a trap.