Acoustics
Adding dense material to a treatment in order to stop sound waves from exiting a source wall, ceiling or floor. Use of Mass Loaded Vinyl, Drywall, Soundproof Sheetrock, Plywood, MDF, Concrete or Rubber. Different widths and densities in soundproofing material reduces sound within a variable frequency range.
Machinery vibrates, causing sound waves in air, hydracaustic waves in water, and mechanical stresses in solid matter. Quieting is achieved by absorbing the vibrational energy or minimizing the source of the vibration. It may also be redirected away from the observer.