Predict a tornado with low-frequency sounds inaudible to human ears?

Research has shown how subaudible sounds can help predict and track tornadoes.

Tornado prediction is important for saving lives. The technology that combines radar or ground-witness reports to make predictions has improved the accuracy of predicting tornado outbreaks for decades, enabling faster evacuation warnings. However, according to the U.S. Meteorological Administration, the false alarm rate of tornado warnings as of 2014 is likely to be at least 50% higher. Now researchers are trying to study the use of low-frequency sounds that are not heard by the human ear as a means to complement the method of detecting tornadoes.

A research team at Oklahoma State University revealed that it started detecting low-frequency signals eight minutes before the formation of a tornado in Oklahoma, and that a characteristic signal appeared five minutes before landing. This feature was revealed using several low-frequency microphones that have been processed to reduce low-frequency noise signals caused by wind.

The research team says there are a number of potential benefits from introducing a low-frequency detector to detect tornadoes. If there is a mountain-like obstacle between the radar detector and the source, the radar will not work, but very low frequencies are not a concern. Some of the deadliest tornadoes occur in the southeastern United States, but those who wish to witness tornadoes in the Great Plains are not visiting the area. That means another monitoring tool is needed here. By combining the radar signal with low-frequency sound data to generate an alarm, it is possible to reduce false alarms.

The research team is currently working on how to separate the signal from noise. Of course, one expert pointed out that when using low-frequency sounds for alarm purposes, the problem is that sound information is transmitted later than radar information, and it may take a full minute or so to detect the sound of a tornado 20 km away with a microphone. However, the development of a low-frequency sound detection system is raising expectations. Related information can be found here .