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Acoustics of Noise

by | Mar 11, 2022 | Noise Pollution, Pollution

Industrial Noise Control

Tackling noise pollution in an industrial environment is a challenging but necessary task. Industrial Noise Control is essential to provide a safe working environment for industrial workers. Systems can use noise control products such as those mentioned below to attenuate noise.
1. Industrial Fan Silencers: Fans are an essential part of almost every industrial appliance. They help in cooling down machinery that heats up. However, they contribute to industrial noise. Manufacturers can fit machines with fan silencers and exhausts to reduce noise effectively.
2. Duct Lining: Ventilation and cooling systems typically generate much noise. Lining ventilation or cooling ducts with sound absorbent material can go a long way in reducing noise.
3. Noise Control Enclosures: Employers can put up enclosures around noisy equipment. Enclosures ensure that noise is contained within the chamber and does not affect people working outside it.
4. Vibration Isolation Pads: Equipment that contains vibrating components produces much noise. Using anti-vibration elements like springs can significantly reduce the noise generated by vibration.

Effect of Noise on Workers’ Efficiency

effects of noise on workers efficiency There have been several studies on how background noise in an office impacts workers’ performance. While the total time duration of exposure to noise does not significantly impact a worker’s performance, the noise itself causes workers to perform their tasks less efficiently. Employees complain of annoyance, headaches, and problems concentrating on being exposed to noise in an office. However, the impact noise has on productivity differs from person to person. Noise might cause minor aggravation in one person and might greatly hinder the work of another. Studies have found that most people get annoyed by low-frequency noise. Studies also found symptoms of fatigue in workers irritated by low-frequency noise, which led to a decrease in job performance. Therefore, there exists a crucial link between exposure to noise and the working efficiency of a person.

Acoustic Quieting

Acoustic quieting is the process by which noisy machines are made quieter. The leading cause of noise from a machine is vibration. Acoustic quieting dampen these vibrations, so noise cannot reach a worker or person. There are three methods of acoustic quieting.

  1. Absorbing the vibrational energy
  2. Reducing the vibration of components in a machine
  3. Directing the vibrational noise away from a receiver

Initially developed for military purposes, acoustic quieting aimed to hinder the detection of submarines through sonar. Today, industrial applications use the adaption of the same technology.

Mechanical Isolation Technique

The mechanical isolation technique is mainly used to protect industrial workers from toxic and flammable substances. However, employers can also use it to protect workers from noise pollution. Employers can mechanically isolate equipment and machinery by directing workers to introduce an element or a break to prevent noise transmission from the source to the receiver. Some techniques of mechanical isolation are: Air gapping isolation Here, workers introduce a physical separation between the noise source and the equipment. This technique involves removing a section from the piping (or any other segment) of the equipment to block noise transmission from the source. Single valve isolation Just as the name suggests, only one valve is used here to isolate the source of noise from workers. Double block and bleed isolation In this technique, two valves are used in series. Noise passes between the two valves and through a vent. The vent opens up in a safe location, away from the working area. This technique is considered the most secure form of isolation.

Acoustical Absorption

Acoustical absorption Acoustic absorption or sound absorption is a method of reducing noise through the absorption of sound waves by an absorbent material such as fiberglass placed on ceilings, walls, and floors. These materials absorb sound preventing them from reflecting and transmitting, thus reducing noise. Acoustic absorption plays a significant role in the acoustics of spaces such as:

  • Concert venues
  • Theatres
  • Churches, cathedrals, and other places of worship
  • Schools
  • Recording studios

There are three main types of acoustic absorbing material used. They are:
1. Porous Absorbents
Porous absorbents include foam and fibrous material. Fibrous materials act as excellent sound absorbers. When sound waves meet a fibrous surface, it causes the material fibers to bend. This bending generates heat. Thus, acoustic energy gets converted to heat energy, which results in the absorption of noise.
2. Resonance Absorbents
The structure of a resonance absorbent consists of a solid plate with an air space behind it. These achieve maximum noise absorption when the frequency of noise matches the resonant frequency of the absorbent. Alternatively, manufacturers of absorbents fill the air space with a porous material to gain a broader range of frequency absorptions.
3. Single Absorbents
Single absorbents include objects such as chairs, tables, and other materials. These are not very effective in absorbing noise but do provide relief.

Public Education

The public must be fully aware of the harmful effects of noise pollution on their health and the environment. They should also be aware of the steps they can take to reduce noise. Including courses on noise pollution in schools plays a significant role in achieving these objectives. Universities should encourage students studying acoustics to participate in international conferences where Information exchange between people from different countries can help raise awareness about new noise control measures and improve existing ones. Developing policies that let government authorities (national and local) disseminate information about noise control measures to the public is essential. Once people are entirely aware of the health hazards of noise pollution and the need to control it, they can reduce noise pollution significantly. Also, in some cases, the reduction of noise pollution automatically results in decreased air and water pollution. For example, reduced noise pollution from road traffic leads to less air pollution caused due to road traffic.

Other Non-Legislative Measures

Many NGOs are working towards raising awareness among the public about the ill effects of noise pollution and how to tackle it. They help communities and societies meet their noise pollution objectives. They also help people in lodging formal complaints against perpetrators and carry out surveys to gauge public attitudes towards noise pollution. Non-legislative bodies form an essential link between the government and the common people. They can pressure government bodies to provide a better environment for the public to live in. Apart from NGOs, individual citizens can take it upon themselves to reduce noise by practicing the following measures:

  1. Avoid using the horn while traveling in a vehicle.
  2. Turn off appliances such as air conditioners and televisions when not in use at home. These can apply unnecessary stress to the ears.
  3. On exposure to loud noises, use earplugs.
  4. When listening to music on earphones or headphones, keep the volume low.
  5. Plant trees. They help improve air quality and also act as a sort of buffer against the propagation of noise. They also absorb sound. Studies have found that trees can reduce noise levels by approximately 5 dB.



  • The author has done a master's in Environmental science and is currently working as chief Environmental Advisor with New Delhi State Government.


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