Flexi Says: The type of vibration that cannot be heard by humans because it is below their hearing capacity is called infrasound.
Vibration, periodic back-and-forth motion of the particles of an elastic body or medium, commonly resulting when almost any physical system is displaced from its equilibrium condition and allowed to respond to the forces that tend to restore equilibrium. Vibrations fall into two categories: free Effects of Vibration on the Human Body Vibration, especially when sustained or resonant, can impose meaningful stress on the human body. The effects of vibration on the human body manifest in physical, neurological, cognitive, and emotional dimensions. Below is an evidence-based overview. Physical Effects of Sound Vibration on the Human Body Musculoskeletal Strain, Pain, and Fatigue ... The type of vibration that cannot be heard by humans because it is below their hearing capacity is called infrasound. Is vibration a bad thing? Vibration can be desirable: for example, the motion of a tuning fork, the reed in a woodwind instrument or harmonica, a mobile phone, or the cone of a loudspeaker. In many cases, however, vibration is undesirable, wasting energy and creating unwanted sound. Is vibration deterministic? In mechanics, vibration (from Latin vibrre 'to shake') is an oscillation of matter about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the oscillations can only be analysed statistically (e.g. the movement of a tire on a gravel road). How does a vibration affect a sound? These properties determine how well an object can sustain a vibration. The frequency of vibrationhow many times it oscillates per seconddetermines the pitch of the sound. Low-frequency vibrations produce deep, booming sounds like a bass drum, while high-frequency vibrations create sharp, high-pitched tones like a piccolo. Do vibrations require oscillatory motion? Vibrations (i.e. the exchange of potential and kinetic energy) require oscillatory motion that may repeat itself regularly or irregularly. A motion that is repeated at time intervals is called periodic motion. The vibrations might not be large enough to be visible. Or the amount of damping might be so strong that the object scarcely completes a full cycle of vibration. But as long as a force persists to restore the object to its original position, a displacement from its resting position will result in a vibration.
