Sound (its occurrence and causes):
Acoustics is a science that studies acoustic phenomena and their laws, and this science is considered one of the sections of wisdom, and its usefulness to music is as the building engineer’s need for basic building materials.
Every body capable of producing vibrations can make noises or sounds, depending on the number of vibrations it sends in a particular unit of time, and their number per second is called (Hertz units) (Heinrich Hertz 1857-1894 AD), a German physicist, As for noise, it is within (16) vibrations per second, while the frequency of the audible sound is between (16-16000) vibrations per second, Suad Ali Hassanein: Teaching Hearing and the Rules of Western Music, p.1
And the sound in general is what happens from every vibrational movement of a resonant body that occurs in the air as a vibration that passes through it to a certain distance, and the sound is that feeling that is transmitted by the ear by the effect of the vibrations of sound bodies. the sound is transmitted through the air in other bodies by means of movements that are transmitted from the sound-generating body and spread In all directions in the form of overlapping circles, as happens when we throw a stone into a body of water.
The sound also occurs from the percussion of a resistant body to a resistant body, which results in a ripple in the air that fills the space between them, and continues to touch the meatus, striking the auditory sense in the form of a ripple and percussion. The melody in terms of congruence and repulsion according to calculated proportions, because the sharpness of the voice, for example, results from the hardness and sharpness of the object being struck, as in stringed instruments, or the narrowness of the air outlet and the shortening of its cylinders close to the position of the blower. The collection and arrangement of the types of sounds, an agreed collection, an agreed transition, and an acceptable harmonious rhythm, is called (melody), and the result of that is called (melody), for melodies are performed by the human voice or by musical instruments.
Sound travels at a speed of 3,400 meters per second, and this is observed when the synchronous movement between lightning and thunder occurs.