Insights into Noise Pollution

Excessive noise, commonly referred to as noise pollution, poses a significant threat to human well-being globally. It primarily stems from atmospheric, environmental, and occupational sources, including industrial machinery and indoor equipment.

Industrial workers often face hazardous noise levels, endangering their health. Despite regulations in many countries aimed at reducing noise hazards, enforcement remains inconsistent, resulting in variations in noise laws and ordinances worldwide.

In order to comprehend the intricacies of industrial noise, and consequently, the techniques employed for soundproofing, it is imperative to embark on an exploration of sound and noise pollution.


Introduction: Classes of noise and noise pollution 

As already discussed in previous publications, noise pollution is the disturbing noise that can harm human well-being, and it has become a significant concern in today’s industrial environments.

Noise is pervasive, with some industrial areas experiencing particularly loud continuous noise. Physically, there’s no difference between sound and noise; noise refers to undesired sound and any unnecessary disturbance within a useful frequency band.

Generally speaking, most outdoor and environmental noise is caused by industrial machines, transportation systems, and indoor activities such as machinery in workplaces, building activities, household appliances, and music performances.

Noise is also defined as unwanted sound and a form of energy emitted by a vibrating body, which, upon reaching the human ear, creates the sensation of hearing through nerves. Not all sounds produced by vibrating bodies are audible; the audible range is typically between 20 Hz to 20 kHz. Frequencies below 20 Hz are called infrasonics, and those above 20 kHz are termed ultrasonics.

Noise can be continuous or intermittent, and it may be of high or low frequency, both of which are undesirable for normal human hearing.

The distinction between sound and noise can also depend on the recipient’s inclination and interest, ambient conditions, and the impact of the sound at that moment. Noise intensity is typically measured in logarithmic units (dB) because this scale allows a wide range of pressures to be described without using large numbers and represents the nonlinear behavior of the ear more accurately.

Let’s examine three distinct classes of noise:

  • Atmospheric noise: This type of radio noise arises from natural atmospheric phenomena, primarily lightning discharges during thunderstorms. Worldwide, approximately 3.5 million lightning flashes occur daily, constituting atmospheric noise, with cloud-to-ground flashes being more prevalent. At very low frequencies (VLF) and low frequencies (LF), atmospheric noise tends to dominate, while at high frequencies (HF), man-made noise, especially in urban areas, is more prominent.
  • Environmental noise: Environmental noise encompasses noise pollution from external sources, primarily caused by transportation systems such as buses, trains, cars, aircraft, and recreational activities like sports and music performances. This type of noise is present in various human activities and can have diverse effects on individuals, ranging from emotional to physiological and psychological. While low-level noise may not be harmful, prolonged exposure to environmental noise can lead to annoyance, sleep disturbances, hearing loss, and stress-related problems. Transportation noise originates from engine/exhaust and aerodynamic sources, while recreational noise can come from various activities and processes. Additionally, background noise from alarms, conversations, and bioacoustic sources like animals or birds contributes to environmental noise.
  • Occupational noise: This refers to noise that affects workers during their job duties, either from the work environment or the machinery they operate. Industrial noise varies in intensity, frequency components, and consistency. Some machinery produces continuous noise with a relatively uniform frequency response and consistent level, while others exhibit intermittent periods of higher noise levels amidst lower background noise.

Technical terms and detailed related to noise pollution

The definitions of key technical terms concerning noise pollution measurement parameters and indicators are sourced from the American National Standards Institute (ANSI) standards, ANSI S1.1-1994 or ANSI S3.20-1995, as per the terminology employed in those standards:

  • Audiogram: A graphical representation of hearing threshold levels plotted against frequency. Frequencies below 20 Hz are termed infrasonics, while those above 20,000 Hz are referred to as ultrasonics.
  • Baseline Audiogram: The initial audiogram against which subsequent ones are compared to assess significant threshold shifts. It is obtained from an audiometric examination conducted before or within the first 30 days of employment following at least 12 hours of silence.
  • Continuous Noise: Noise characterized by negligible fluctuations in level during the observation period.
  • Crest Factor: Ten times the base-10 logarithm of the square of the wideband peak amplitude of a signal to the time-mean-square amplitude over a specified time period.
  • Decibel, A-weighted (dBA): The sound level measured using the A-weighting network on a sound level meter.
  • Decibel, C-weighted (dBC): The sound level measured using the C-weighting network on a sound level meter.
  • Noise Reduction Rating (NRR): An indicator of a hearing protector’s noise reduction capabilities, expressed in decibels (dB). It is a single-number rating required by law to be displayed on the label of each hearing protector sold in the USA.
  • Derate: The process of using a fraction of a hearing protector’s NRR to calculate the noise exposure of a worker wearing that protector.

The Effects of noise pollution on human health

Noise pollution has significant societal costs, prompting commitments from organizations like the European Commission (EC) and the World Health Organization (WHO) to stringent noise reduction targets.

Acute noise exposure triggers the release of stress hormones, such as adrenaline, leading to changes in normal bodily functions. Severe effects can occur even at relatively low environmental noise levels, disrupting concentration, relaxation, or sleep. Night-time noise, in particular, may impact cardiovascular health due to sleep disturbances.

WHO recommends night-time noise levels below 55 dB(A) to prevent adverse health effects in the short term, with a long-term goal of 40 dB(A). Common effects of noise pollution on vulnerable populations include annoyance, sleep disturbance, heart and circulation problems, diminished quality of life, cognitive impairment, and hearing loss. Prolonged exposure to continuous noise levels of 85–90 dB(A) in industrial settings can result in progressive hearing loss, particularly in the frequency range of 3 kHz to 6 kHz. Speech intelligibility can be reduced even at 10 dB, with noticeable social hearing handicaps above 30 dB. The impact of noise on health can vary based on sound characteristics such as intensity, frequency, complexity, and duration.


Industrial soundproofing systems, like those offered by STOPSON ITALIANA, are specifically designed to mitigate the effects of noise pollution in industrial settings. These systems target the type of noise described previously, focusing on reducing noise levels generated by industrial processes and machinery.

By implementing soundproofing solutions from Stopson Italiana, industrial facilities can effectively combat this type of noise, creating a quieter and safer working environment for employees and surrounding communities.

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