Sound energy is the energy produced by sound vibrations as they travel through a specific medium. Sound vibrations cause waves of pressure which lead to some level of compression and rarefaction in the mediums through which the sound waves travel. Sound energy is, therefore, a form of mechanical energy; it is not contained in discrete particles and it is not related to any chemical change, but is purely related to the pressure its vibrations cause. Sound energy is typically not used for electrical power or for other human energy needs because the amount of energy that can be gained from sound is quite small.

Energy is the amount of work that can be performed by a given force, system, object, or anything else capable of performing work. Work is simply defined as the ability to cause change in a system; this can involve anything from a change in location to a change in heat energy. The amount of work that can be performed by common, day-to-day sounds is quite small, so sound is not often thought of in terms of the energy it contains. Sound energy does, however, exist as the vibrational waves of sound cause change, however small that change is.

Rather than measuring sound in typical units of energy, such as joules, scientists and others measuring sound tend to measure it in terms of pressure and intensity using units such as pascals and decibels. Sound measurements are, by their very nature, relative to other sounds that cause more or less pressure. Usually, sound is described in terms of the way it is perceived by healthy human ears. A sound that produces 100 pascals of pressure at an intensity level of about 135 decibels is, for example, commonly described as the threshold of pain because it is of adequate pressure and intensity, often combined into the common term "loudness," to cause physical pain.

Sound energy is closely related to the ability of the human ear to perceive sound. The wide outer area of the ear is maximized to clearly collect sound vibrations. Sound energy is amplified and passed through the outer ear, striking the eardrum which transmits sounds into the inner ear. Auditory nerves fire according to the particular vibrations of the sound waves in the inner ear, which designate such things as the pitch and volume of the sound. The ear is set up in an optimal way to interpret sound energy in the form of vibrations.