The sound produced by the vibration of an object is divided into two categories: musical sound and noise.

Musical sound:

The sound with a fixed pitch produced by the regular vibration of the sound-producing object is called musical sound. Such as piano, violin, erhu, etc. are all musical instruments that can produce musical sounds. Musical sound is the most important and basic material used in music. The melody and harmony in music are all composed of musical sound.

From the perspective of acoustic analysis, music has three main characteristics: loudness (also known as sound intensity), tone (also known as pitch) and timbre, which are called the three elements of music.

Noise:

The standard usage of noise is noise. From a physiological point of view, any sound that interferes with people's rest, study and work and interferes with the sounds that people want to hear, that is, Unwanted sounds are collectively called noise. Noise pollution occurs when noise causes adverse effects on people and the surrounding environment.

In physics, noise refers to all irregular signals (not necessarily sounds), such as electromagnetic noise, thermal noise, noise during radio transmission, laser noise, fiber optic communication noise, and images when cameras take pictures. noise, etc.

Sound characteristics:

1. Loudness:

People subjectively feel the size of the sound (commonly known as volume), which is determined by "amplitude" and the distance between the person and the person. The distance from the sound source is determined. The greater the amplitude, the greater the loudness. The smaller the distance between the person and the sound source, the greater the loudness.

2. Pitch:

The level of sound (treble, bass) is determined by "frequency". The higher the frequency, the higher the pitch (frequency unit is Hz (hertz), Hertz, the hearing range of the human ear is 20 to 20,000 Hz. Below 20 Hz is called infrasound, and above 20,000 Hz is called ultrasonic wave). For example, low-end sounds or higher sounds, such as fine string sounds.

3. Frequency:

Frequency is the number of sound waves passing through a given point per second. Its unit of measurement is Hertz, named after Heinrich Rudolf Hertz. named. This person sets up a table to demonstrate how frequency is related to cycles per second.

1 kilohertz or 1000 Hz means that there are 1000 cycles of sound waves passing through a given point per second, 1 megahertz means 1,000,000 cycles per second, and so on.