Ear protectors are personal protective articles that protect people's hearing from strong noise damage.

If noise reduction is technically or economically difficult, the use of ear protectors is the most economical and effective way. Types can be divided into earplugs, ear muffs and anti-noise helmet 3 categories.

Ear protectors can be called ear caps or ear muffs, a type of ear protector that covers the entire auricle.

The earmuffs are composed of two round shells connected by a bow frame made of plastic. The shells are composed of wool or fluff, and the overall shape is like headphones.

① Earplugs: can be inserted into the external ear canal or inserted in the entrance of the external ear canal, suitable for noise environment below 115 decibels.

It comes in two types: plastic and non-plastic. Plastic earplugs are made of wax-soaked cotton yarn, anti-sound glass wool, plasticine and other materials. The user can shape it at will and use each piece once or several times.

Non-plastic earplugs, also known as "universal earplugs", are made of plastic, rubber and other materials, and come in a variety of sizes. Dozens of earplugs have been made in China.

Ear muffs: shaped like earphones, mounted on the bow to cover the ear to attenuate the noise device. The noise attenuation of the earcup can reach 10 ~ 40 decibels, which is suitable for environments with high noise, such as shipyards, processing workshops of metal structure factories, and engine test stands. In recent years, some countries have also fixed earmuffs on welding masks or combined with communication headsets or earphones.

Earplugs and earmuffs can be used alone or in combination. The combined use can increase the noise attenuation by 5 ~ 15 decibels compared with the single use.

③ Anti-noise helmet: most of the head can be protected, such as ear muffs, the anti-noise effect is better.

This helmet has anti-noise, anti-collision, anti-cold, anti-storm, anti-shock and other functions, suitable for strong noise environment, such as shooting range, tank cabin inside and other high noise, high shock environment.

Of course, earplugs also have disadvantages, because earplugs are sealed relative to the ear, which will lead to no air circulation in the ear, and it is easy to produce a relative temperature increase in the ear, which is not conducive to ear health.

The evaluation of ear protectors is mainly measured from the aspects of acoustic attenuation, comfort, irritation, convenience and durability.

① Acoustic attenuation: expressed by the difference between the hearing threshold when wearing ear protectors and bare ears. The greater the difference, the better the performance of the ear protector. Ear protectors can reduce noise by 10 ~ 45 decibels. There are two methods to measure the acoustic attenuation of ear protectors: subjective test (real ear method) and objective test (artificial ear method).

The former is a psychophysical method, which measures the difference between the threshold of hearing with and without ear protectors in a free sound field. The latter is a physical method, using physical instruments instead of human subjective responses to test the acoustic attenuation of ear protectors.

Comfort: It is the subjective reaction after people wear ear protectors. From the actual use of ear protectors, whether ear protectors can be widely used is mainly whether they are comfortable after wearing.

(3) Irritability, convenience and durability: irritability refers to whether the ear protector has a stimulating effect on the vast majority of people after wearing it for a period of time, and whether it will cause skin allergies.

Convenience refers to whether the ear protector is simple in structure and easy to wear, with strong adaptability. Durability refers to the length of service life of the ear protector, which is not easy to age and not easy to damage