Physics of Sound

What is sound?
Sound is vibrations. It travels through air but it can also travel through other mediums, both liquids and solids. The vibrations are transferred by being passed on from particle to particle. When these vibrations meet your ear they travel through the ear to the cochlea. The cochlea is filled with fluid and when the vibrations reach it, they transfer to little hairs that are connected to the auditory nerve. The vibrations are then converted into nerve impulses which are sent to the brain where you perceive them as sound.

Waveform Properties
Sound travels in waves. There are a few aspects to these waves that affect how the sound is heard.

One aspect of the wave is it's amplitude. This is the height of each wave and determines how loud the sound is. The higher the amplitude the louder the sound will be. Amplitude is measured by the amount of force it applies to an area. The most commonly used unit for this measurement is decibels, however it is also measured in newtons per square meter (N/m2).

Another aspect of the wave is it's length. The wavelength is the length of each wave and is the main aspect that effects the pitch of the sound. The shorter the wavelength, the higher pitched the sound will be. Wavelength is measured in normal units of distance measurement.

Another aspect of the wave is it's speed. The wave speed is the speed at which the sound travels and has an affect on the pitch of the sound. The speed of the waves is determined by the density of the medium the vibrations are travelling through. For example, sound travelling through air will travel slower than a sound travelling through water.

The fourth and last aspect of sound waves is the frequency. Frequency is the number of waves per second and is affected by both the wavelength and the wave speed. It is the main way of displaying the pitch of a sound, the higher the frequency, the higher the pitch. The unit of measurement of frequency is Hertz (Hz).