The agency has also tested about a half-dozen ultrasonic devices that plug into wall sockets and found they do not work either.

Scatter guns are another form of ultrasonic device.

The problem with current ultrasonic devices, he said, is that they do not usually penetrate the walls and floors, where rodents usually stay.

These range from backyard misting systems to bug zappers to ultrasonic devices.

In dentistry, ultrasonic devices are sometimes used to remove calcium deposits from the surface of teeth.

There are ultrasonic devices available to do this in the laboratory.

Working with his brother Thomas, he developed an ultrasonic device designed to disrupt the deer's hearing.

Simple ultrasonic devices - to measure water level in a stilling well or directly in a canal.

For example, peer-reviewed publications have consistently shown that ultrasonic devices do not drive unwanted animals away.

Increasingly, the processing for ultrasonic devices will be done by software in computers that themselves are getting smaller, he said.