1、 The hazards of environmental noise pollution

The impact and harm of noise on the human body can generally be divided into two aspects: labor protection and environmental protection. The former refers to the harm to human health, leading to the occurrence of various diseases, while the latter refers to the disturbance of the quiet environment, affecting people's normal work and life. The main hazards of noise to human health are: damage to hearing, causing noise induced hearing loss; Causing excitation and imbalance in the cerebral cortex, damage to cerebral vascular function, and leading to neurasthenia; Damaging the cardiovascular system, causing digestive system disorders, and affecting endocrine function; Disturb people's normal lives, rest, language conversations, and daily work and study, distract attention, and reduce work efficiency. Most residents easily overlook the harm caused by elevator noise, as the noise generated by elevators is generally low to medium frequency, and the human ear is not very sensitive to low frequencies. However, through practical research, we have found that low-frequency noise may also affect human visceral health.

In most residential buildings in Beijing, elevators are designed and installed just one wall away from the bedrooms of residents. During inspections in some residential areas, it was found that the noise generated by elevators at night can reach up to 42 decibels. According to relevant national regulations, the noise emitted at night cannot exceed 35 decibels. Elevator noise can interfere with residents' normal rest, such as hindering students from doing homework, harassing us from watching TV programs and talking on the phone, and seriously causing adverse reactions such as headaches, palpitations, and brain swelling.

2、 Basic principles of noise control

The formation of noise pollution is mainly caused by three factors, namely: sound source, propagation medium, and receiver. Only when these three factors coexist can they interfere with the listener. Starting from these three aspects, the goal of controlling noise can be achieved by reducing the sound source, limiting noise propagation, and blocking noise reception. In specific noise control technologies, measures such as vibration isolation, sound absorption, sound insulation, and noise reduction can be adopted.

Sound absorption: When sound waves are incident on the surface of an object, some of the sound energy needs to be absorbed by the object and converted into other forms of energy, which is called sound absorption. The sound absorption performance of materials is represented by the absorption coefficient, and the larger the absorption coefficient, the better the sound absorption performance of the material. The sound absorption performance of materials is related to their properties, structure, incident angle of sound waves, and frequency of sound waves. The sound absorption mechanism of porous sound-absorbing materials is that there are countless small interconnected pores inside the material. When sound waves are incident on the surface of these materials and then enter these small pores, it causes air movement inside the pores. The air close to the pore wall and fiber surface is not easily moved due to friction and viscous motion resistance, which converts sound energy into heat energy and consumes it. Therefore, sound-absorbing materials with good performance should be porous, with interconnected pores, and the interconnected pores should be connected to the outside to allow sound waves to enter the interior of the material.

Sound insulation: The method used for sound insulation is to enclose the noise source and control the noise within a small space. This type of sound insulation structure is called a soundproof enclosure. When sound waves encounter a shielding object, due to the change in interface characteristic impedance, a portion of the incident sound energy is reflected, a portion is absorbed, and a portion of the sound energy continues to propagate through the shielding object. The sound insulation performance of materials can be represented by the sound transmission coefficient. The smaller the sound transmission coefficient, the less sound energy is transmitted and the better the sound insulation performance of the material. The sound insulation performance of materials is related to the structure, properties, and frequency of the incident sound waves of the sound insulation body.

Noise reduction: Noise reduction is the process of fixing porous sound-absorbing materials on the inner wall of an airflow channel or in a certain way in a pipeline to weaken aerodynamic noise. The noise reduction level can generally reach 15-40 decibels.

3、 Governance technical measures

Addressing elevator noise requires attention to three main aspects. Firstly, during the elevator design phase, the installation location and method of the elevator should be considered, as well as proactive sound insulation and noise reduction measures such as machine room sound insulation; Secondly, elevator production units should use vibration isolation equipment and facilities that have been strictly calculated; Thirdly, elevator users should strengthen maintenance and upkeep to ensure normal operation.

We know that as a large device, the high-speed operation and starting of the motor during operation and stopping, as well as the brake engagement and extension during parking, determine the inevitability of noise and vibration in elevators. Therefore, the country has made relevant regulations on elevator noise standards: "According to the latest elevator noise standards formulated in 2003, the measured elevator noise value in the elevator machine room should be ≤ 80 decibels

The real impact on the owner's home is not the noise A-level value specified by our regulations or what we consider, but the low-frequency vibration during elevator start-up, operation, and braking, and these low-frequency vibrations pose the greatest harm to human health! At present, the country has not formulated standards for low-frequency vibration noise. From another perspective, the widespread phenomenon of elevator noise is also an inevitable result of the rapid development of elevators and real estate in recent years! Because elevators and real estate have a history of over a hundred years abroad, while China has to digest all the technologies and lacks experience accumulation in just over a decade.

Our company has collaborated with the Acoustic Laboratory of the School of Architecture at Tsinghua University. Based on years of experience in elevator noise reduction engineering and a series of environmental noise reduction engineering solutions, we have designed an environmental noise reduction solution specifically for elevators based on the principle of elevator sound resonance. By gradually reducing the vibration and operating noise of the elevator within the elevator specific soundproof layer designed by our company, we can achieve thorough reduction and digestion. By controlling the sound source reduction of the noise, we can achieve elevator noise reduction treatment and solve the impact of elevator noise on owners. The measures are as follows:

Noise reduction in elevator shaft

A Fill the construction holes and gaps in the elevator shaft with HOREQ-D5 or cement mortar, and then level them with sealant or cement mortar;

B Polymer mortar bonded to 50mm thick HOREQ-D2 sound-absorbing cotton board.

c. What? 8 fixed nails, with a mid-range of 600mm;

2. Noise reduction in traction machine vibration reduction room

A Install a mud blocking and vibration reducing device on the lower steel beam of the traction machine

B Noise reduction treatment in the computer room (method as above)

4、 Noise reduction effect

Through years of engineering practice and accumulation, analysis, and summary of engineering noise reduction data. We conclude that after the above noise reduction methods, the noise inside the elevator machine room can usually be reduced by 15dB, and the residential rooms below the elevator machine room can also achieve a reduction of 7dB.