Acoustics is a branch of physics that studies mechanical waves and how they effect gases, liquids and solids. This field covers how mechanical energy such as sound or vibration emanates from its source and how it carries and echoes as it encounters walls or other obstacles.
Acoustical topics also include the fields of vibration and ultrasound and infrasound (range of sounds that are above and below human hearing range). This science is also used in the building of auditoriums and theaters for maximum sound fidelity. Acoustic research can also focus on the study of animal communication such as subsonic and ultrasonic sounds made by elephants and sea mammals as well as technologies that use vibration.