As stated by The Physics Classroom, “all objects have a natural frequency or set off frequencies at which they vibrate.” This extends to all matter, as everything in the universe is constantly vibrating, and each object’s unique properties determine its range of frequencies. This principle applies to people as well. For example, one study found that the standing human body’s resonant frequency (natural frequency) is between 9 and 16 Hz.
For reference, the Earth’s resonant frequency, also called the Schumann resonance, is about 8 Hz, and the frequency of the brain when relaxed, meditative, or daydreaming (Alpha waves) is around 8 to 13 Hz. Theta brainwaves, associated with deep meditation, internal awareness, and the time between sleep and wakefulness, are 4 to 8 Hz.