Ultrasound and Animals

Bats

Bats use a variety of ultrasonic ranging (echolocation) techniques to detect their prey. They can detect frequencies as high as 100 kHz, although there is some disagreement on the upper limit.

Dogs

Dogs can hear sound at higher frequencies than humans can. A dog whistle exploits this by emitting a high frequency sound to call to a dog. Many dog whistles emit sound in the upper audible range, but some, such as the silent whistle, emit ultrasound at a frequency in the range of 18 kHz to 22 kHz.

Dolphins and Whales

It is well known that some whales can hear ultrasound and have their own natural sonar system. Some whales use the ultrasound as a hunting tool (for both detection of prey and as an attack).

Fish

Several types of fish can detect ultrasound. Of the order Clupeiformes, members of the subfamily Alosinae (shad), have been shown to be able to detect sounds up to 180 kHz, while the other subfamilies (e.g. herrings) can hear only up to 4 kHz.

Moths

There is evidence that ultrasound in the range emitted by bats causes flying moths to make evasive manoeuvres because bats eat moths. Ultrasonic frequencies trigger a reflex action in the noctuid moth that cause it to drop a few inches in its flight to evade attack.

Rodents/Insects

Ultrasound generator/speaker systems are sold with claims that they frighten away rodents and insects, but there is no scientific evidence that the devices work. Laboratory tests conducted by Kansas State University did show positive results for products from specific manufacturers. Controlled tests on some of the systems have shown that rodents quickly learn that the speakers are harmless. The positive results (Kansas State University) were limited to units which use constantly modulating frequencies . The frequency used however is often within the range that most children can hear, and can cause headaches.

Mosquitoes

There is a theory that ultrasound of certain frequencies, while not audible to humans, can repel mosquitoes. There are computer programs available on the internet that claim to use this phenomenon for pest control. There have been mixed reports about the effectiveness of this method towards mosquito control.^{[dubious – discuss]} These claims are made questionable by the fact that most if not all computer speakers and the soundcards that drive them are incapable of producing sound far beyond the upper and lower ranges of human hearing.