Plants are far more sensitive than people give them credit for. Some plants respond when insects touch them, others turn towards light sources, and others can detect other plants growing around them. However, researchers have recently found indications that plants can make sounds when they are placed under stress. Similar to animals, it was found that plants can audibly vocalize their agony when deprived of water or forced to endure bodily harm.
The sound is undoubtedly too high for humans to hear as the sounds made are in the ultrasonic range. In a recent experiment by a team of plant scientists at Tel Aviv University, a microphone was placed beside some tobacco and tomato plants after their stem was snipped off. They found that the tobacco plants produced an average of 15 sounds an hour after being cut, while the tomato plants produced 25 sounds an hour. These sounds ranged between 20 and 150 kilohertz.
When those sounds were analyzed using a computer, it was able to distinguish the type of stress the plant was under, or if it was normal sounds. The sounds, although undetectable by humans, could potentially be heard by animals or other plants. The source of the sounds is still unclear though researchers have theories about what is causing them. However, this data is still preliminary, and further studies still have to be done to find the purpose of these sounds, and if the type of plant has any influence on the sounds produced.