| What is Sound? |
In physical terms, sound is the mechanical vibration of a gaseous, liquid or solid elastic medium. Sound is a form of mechanical energy. It is produced, when particles oscillate around their equilibrium position. |
| In physical terms, sound is the mechanical vibration of a gaseous, liquid or solid elastic medium. Sound is a form of mechanical energy. It is produced, when particles oscillate around their equilibrium position. In this brochure, we will deal with sound in air (airborne sound) and sound/vibrations in solid medium as the steel construction of a vessel (structureborne noise). Propagation of sound in air happens, when a sound source, usually a vibrating object mechanically affected, makes the air molecules next to its surface oscillate around their equilibrium position in the stagnant air. |
| Due to the elasticity of the air the sound is propagated through the air by successive oscillations of the neighbouring elastic air particles, and we have a steadily progressing sound wave. If the sound source is vibrating harmonically, the fl uctuations of the air particles will be harmonic too, and this in any arbitrary point. In a sound wave in air the particles will oscillate in the same direction as the wave front propagates (=longitudinal wave), and this creates areas with higher respectively lower pressure compared to the atmospheric pressure. Therefore sound waves can be treated as pressure waves.  |
