What does 18 Hz frequency do

The most dangerous frequency is at the median alpha-rhythm frequencies of the brain: 7 hz . This is also the resonant frequency of the body’s organs.

The key here is frequency: 19hz is in the range known as infrasound, below the range of human hearing , which begins at 20hz.15 Eki 2003

Sound at 20-200 Hz is called low-frequency sound, while for sound below 20 Hz the term infrasound is used.