Sound Freebies is generally known as vibrational transmission of mechanical energy that propagates through matter as a wave (through fluids as a compression wave, and through solids as both compression and shear waves) that is audibly perceived by a living organism through its sense of hearing Sound Freebies. For humans, hearing is limited to frequencies between about 20Hz and 20kHz, with the upper limit generally decreasing with age. Other species have a different ranges of hearing Sound Freebies. For example, dogs can perceive vibrations higher than 20kHz. Sound doesn't require an external source and the brain of an organism can synthesize sound on it's own Sound Freebies.
Sound Freebies is further characterized by the generic properties of waves, which are frequency, wavelength, period, amplitude, speed, and direction (sometimes speed and direction are combined as a velocity vector, or wavelength and direction are combined as a wave vector).
The mechanical vibrations that can be interpreted as Sound Freebies can travel through all forms of matter, gases, liquids, solids, and plasmas Sound Freebies. The matter that supports the sound is called the medium. Sound propagates as waves of alternating pressure, causing local regions of compression and rarefaction. Particles in the medium are displaced by the wave, and oscillate Sound Freebies. The scientific study of the absorption and reflection of sound waves is called acoustics Sound Freebies.