It is important to understand what sound is to be able to understand the workings of the ear, how sound is created, and what technological advancements have been made in sound technology. His knowledge will help you understand how music is made, hear and determine the level of noise that the human ear can tolerate.

Sound is made up of vibrating particles and mechanical waves. A vibration is required for sound to be created. You can think of the vibrations of a drum, the vocal chords, the membrane of a loudspeaker and many more. It must be propagated in a medium, which can either be liquid, solid or gas. Air at rest is what we will use for simplicity. The sound source is able to displace any air particles (molecules) that come into contact with it from their equilibrium positions. These particles vibrate around their equilibrium positions.

This is what a spring does, when it's stretched and released. The vibration is transmitted to adjacent particles, and so forth. This vibration is transmitted in the direction wave propagation. We call it a longitudinal mechanical waves. A transverse wave would be formed if the vibration was perpendicular with the propagation.

Solids can propagate sound with both longitudinal and transverse frequencies.

Only longitudinal in liquids and gases

In the direction of propagation, the vibration of air particles creates zones with high and low densities. This is similar to saying that there are areas with more pressure than areas with less. When we listen to high-power music, this effect can be felt in the vibrations of our pants and skirts. Sound propagation, unlike light propagation, requires a medium to propagate. The sound that is produced by an explosion in the atmosphere cannot reach the earth.

Now we can see the properties of sound. The speed tells us how long it takes for a particle of vibration to travel from one to the other. The speed of sound depends on how close the particles are. Temperature and height are important factors in the speed of sound in air. At sea level, sound travels at 1,193 km/h. It is approximately 1,125 km/h if we travel up to the Himalayas. This depends on the temperature. Additionally, sound travels at a faster speed in solids than liquids and at a higher rate in liquids than in gas. The Indians listened to horses trot, and brought their ears to the ground. The time it takes for each particle of matter to create a complete vibration is another property. This property is known as frequency, and it is measured in hertz.

One cycle (vibration) is equal to one hertz. The human ear can hear sounds between 20 and 22,000 hertz. The frequency is related to the tone and other concepts related to music. The sound source provides energy to the medium through which the sound is propagated. The energy from the source will cause more particles to be displace. The energy delivered to the medium per unit time and area is called sound intensity, and the energy per unit time is called power. The audible frequency range can be very wide so a unit that measures loudness is based upon a scale of 10 is called the decibel. A sound that is 20 decibels louder than one that is 10 decibels will be 100 times as intense. This explains the guitar string and flute, as well as many other aspects of sound.