Sound is a kind of energy.

SOURCES OF SOUND
Any vibrating object acts as a source of the sound. The source of the word is called vibration. Sound can be solid, liquid, or gaseous. Let us know about some of the sources of sound making. Origin of sound as a result of vibration: Some sand particles are spread on a thin tin sheet firmly attached to a pillar. When you pull the plate with your hand, you can see that the particles are jumping and making a sound. So, it can be said that vibration produces sound. The human larynx produces sound: The human larynx has two thin membranes. The sound is created by the vibration of those two screens while speaking. The two ends were pulled together by a metal wire with two scaffolds. If you place a piece of paper on the wire and lightly pull the wire, you will see that the paper is shaking and a sound is being made. So again it is understood that vibration produces sound.

PROPAGATION OF SOUND
Inert media is needed to spread the sound. This can be a solid medium, liquid medium, or gaseous medium. Sound cannot spread through zero media. Let’s take a look and see that the mouth of a glass jar is tightly closed with a rubber stopper and two conductive wires are inserted through the stopper and added to an electric clock so that the bell does not touch the jar. This time bell with the bell was mounted on the plate of an exhaust pump. Then, when the bell is rung with the help of an electric wire, its sound can be heard in a very loud pair. When the inside of the jar is emptied by running the pump, the sound of the bell becomes weak.
sounds can also spread through solid mediums. If you can stand on the railway line, you can hear the train coming from far away. Also, if you make a noise on one side of the door, it can be heard quite loudly on the other side. Sound propagation also occurs through a liquid medium. When the bell rings in the water, the fish run towards it. The velocity of sound through solid is greater than that of liquid and gaseous medium and the velocity of sound through liquid is greater than that of the gaseous medium.

PROPERTIES OF SOUND
Sound reflection: The wavelength of sound is much larger than the wavelength of light. So the reflector needs to be much bigger to reflect the sound. Walls, hills, etc. act as reflectors of sound. We occasionally use a microphone when talking. With the help of which the sound can be heard very loudly.
Echoes of words: When a word originates from a source, reflecting a distant reflection when it is heard separately from the original word, then that individual word is called echo of the original word. It can be used to measure the depth of the ocean, to determine the altitude of an aircraft, to determine the speed of sound in the air.

CHARACTERISTICS OF SOUND
The amount of sound energy that flows per second through a single area of a plane perpendicular to the direction of sound propagation is called the intensity of the sound. The intensity of the sound depends on the size of the sound, the distance of the listener, the amplitude of the sound, the density of the medium, the speed of the medium, and so on.
A basic feature of melodic sound is pitch. The characteristic of a melodious sound, which distinguishes it from a melody of the same intensity, is called pitch. Pitch depends mainly on the frequency of the melodic sound. It also depends on the intensity of the sound.
The characteristic of a melodic sound that distinguishes between melodies of the same intensity and sharpness emanating from different musical instruments is called vocal quality. The quality of the vowel depends on the number of syllables present with the original syllable, the ratio of the frequency of the syllable, and their relative strength.