Statens Skadedyrslaboratoriums sammenfatning af testen fra 1976

"An ultra sound device was tested on brown rats. The ultrasound apparatus producing 3 different frequencies, was installed above the passage between 2 laboratory breeding roorns (3. 5 m x 4. 0 m) where 10 brown rats were establisbed a week before.
The amount of food consumed in each room was used as an indication of where the rats preferred ta stay.

As can be seen from Table 10, no strong repellent effect could be observed with a single ultrasound generator in room 521.

With 2 generator in the same small room some effect could be obtained, but as soon as food was removed from the other room the rats did not hesitate to feed in room 521 in spite of the sound generators."