Sound waves like all other waves (but electromagnetic radiation) need a medium to travel, and in a human conversation this medium is usually air. The amplitude of the wave (how far such wave extends from a node) determines the sound's loudness while the frequency (commonly measured in hertz) gives us information on how many wavelengths pass through a certain point per second. Sound waves are sinusoidal and this means that they take the form of trigonometric functions. The formula for waves is:

Where "A" is the amplitude, "w " is the frequency of the wave, "t" is a variable, and "k" is the phase shift of the wave.

Waves can go through either constructive or destructive interference. Destructive interference results when the through of one wave meets the peak of another. This may result in complete destruction of the wave if the two waves have the same amplitude, frequency, and interfere with each other with a 180^o phase shift in respect with each other. In most cases though, this will not occur and the destructive interference will simply result in a new wave with a smaller amplitude. Constructive interference will occur when the peak of a wave meets the peak of another wave. The result of this type of interference is a new wave with a larger amplitude than any of the starting ones.

Shock waves take place whenever supersonic speeds are reached and surpassed. For example, a jet plane surpasses the speed of sound so it creates a shock wave by making the air that it leaves behind less dense.

Physical objects have a natural frequency. This means that every molecule in a system and every system that is allowed to will vibrate or move with the same frequency if left alone- its natural frequency. When an outside force vibrates with a frequency increasingly closer to the natural frequency the amplitude of the vibrations increases and beats are produced. If the outside frequency matches the natural frequency of the object a phenomenon known as resonance will take place. This means that the molecules that make up the object will start vibrating with an increasing amplitude until the force is large enough to overcome intermolecular forces and separate the molecules.