# How to calculate the noise of Industrial Fan

As a device with a geared motor, industrial large ceiling fans will naturally generate noise. Although the industrial fan is mostly used in noisy environments such as workshops and workshops, the noise generated is not enough to exceed other noises in the workshop, but we still need Understand noise and its calculation and evaluation methods.

In the Industrial Fan, in addition to the wind noise generated during operation, the gear of the geared motor is one of the larger noise sources. Whether the noise of the gear device can be reduced has become one of the benchmarks for judging the quality of the Industrial Fan. So how is the noise calculated? Let's start with the sound.

Sound: Sound is a reflection of the vibration of an object being transmitted to human ears through the air as a medium. Therefore, sound is the result of pressure waves generated in the air. These pressure waves have two important characteristics: 1. Amplitude-the size of the volume, in decibels. 2. Frequency-the pitch of the sound, the unit is cycles per second or hertz. Usually the sound standard reaches 85 decibels, and when the frequency is above 3000 Hz, everyone calls this result noise.

DB: It is a unit of sound pressure level. It is a logarithmic unit and has no dimension. It comes from telecommunications engineering. In telecommunications engineering, the gain of an amplifier is expressed by the common logarithm of two power ratios, and its unit is called Bell. The decibel is 0.1 bel, so the decibel is the unit of 10 times the common logarithm of the ratio of two powers. In acoustics, the sound pressure level (decibel value) of a certain sound pressure is the result of the ratio of a certain sound pressure and the reference sound pressure multiplied by 20 by the common logarithm. Therefore, every 20 decibel change in sound pressure level is equivalent to 10 times the sound pressure value change.

Loudness level: The human ear's perception of sound is not only related to sound pressure, but also to frequency. Under the same decibel level of sound pressure level, the high frequency sounds much louder than the low frequency. Based on the characteristics of the human ear, people follow the concept of sound pressure level to derive a frequency-related loudness level, and its unit is defense. And choose the pure tone of 1000 Hz as the reference sound. For example, if a certain noise sounds as loud as a reference sound with a sound pressure level of 90 decibels and a frequency of 1000 Hz, the loudness level of the noise is 90.