Noise adversely affects the economy by reducing productivity, increasing healthcare costs, affecting property values, and negatively impacting tourism and related businesses.
NOISE POLLUTION REGULATION
The Supreme Court highlighted the adverse health effects of prolonged exposure to high-decibel noise, particularly on children, the elderly, and those with medical conditions, and the importance of enforcing noise pollution regulations to protect public health and order. It stated that loudspeakers are not essential for any religion and that religious places cannot claim a right to cause noise nuisance. It has restricted loudspeakers and public address systems between 10 p.m. and 6 a.m. to closed premises like auditoriums, conference rooms, community, and banquet halls. The Noise Pollution (Regulation and Control) Rules of 2000, set decibel (dB) limits and restricted hours for noise pollution. Noise pollution is measured with sound level meters on a logarithmic scale; a 10 dB increase means a doubling of perceived loudness. The permissible limit during daytime and night respectively is 75 dB and 70 dB for industrial areas, 65 dB and 55 dB for commercial areas, and 55 dB and 45 dB for residential areas. Noise is harmful above 75 dB and is painful above 120 dB. The peripheral noise level of a privately owned sound system or instrument is restricted to within 5 dB of the limits specified for that area. Areas around hospitals, educational institutions, court complexes, and government office complexes are notified as silence zones. Despite the Supreme Court criticism, and the National Green Tribunal directions, few states have implemented the rules.
DESIRABLE SOUND, UNDESIRABLE NOISE
Not all sound is considered noise pollution. The human hearing range is from 20 Hz to 20,000 Hz, but sensitivity to higher frequencies decreases with age. Dogs can hear a wider range of frequencies from around 67 Hz to 45,000 Hz, Elephants can register frequencies between 0 and 20 Hz (infrasound), and bats use frequencies above 20,000 Hz (ultrasound) to echolocate. In animals, noise interferes with alerting sounds, altering predator or prey detection and avoidance. It interferes with their reproduction and navigation and contributes to permanent hearing loss. The main noise sources are power tools, electrical generators, machines, construction activities, transport (traffic, rail, airplanes), and propagation (loudspeakers, amplifiers) systems. Poor urban planning such as permitting industries near residential buildings is a major problem. Unauthorised factories, workshops, and warehouses in residential areas are causing severe sound and air pollution, groundwater contamination, and traffic congestion leading to public protests.
NOISE MAP: A noise map shows sound levels with different colour codes during specific time intervals. 2D noise maps demonstrate the variation of noise levels over an area, while 3D maps reveal noise levels at various heights. There are many noise mapping services in India. Noise mapping helps identify and mitigate the sources of excessive noise. As per the 2018 Central Pollution Control Board (CPCB) survey, Chennai is the noisiest metro city in India, followed by Hyderabad, Kolkata, Bengaluru, Mumbai and Delhi.
NOISE HAZARDS AND EFFECT ON ECONOMY
Noise-induced hearing loss is a professional hazard for soldiers (especially gunners), traffic police, construction, industrial, and mining workers. A noise dosimeter records the accumulated personal noise exposure. The National Institute for Occupational Safety and Health (NIOSH) smartphone app can be used instead of a dosimeter. Loud noise causes increased heart rate, constriction of blood vessels, rapid shallow breathing, and altered brain function, leading to mood swings, anxiety, and other mental health problems. Acute Acoustic Trauma (AAT) due to a sudden, intense noise exposure such as a close-range explosion (during war, mining, fireworks, etc.) can lead to permanent hearing loss. Misophonia is a condition where certain sounds trigger intense emotional or physiological reactions, and affect combat and industrial performance. Irritability, civil disturbances, sleep deprivation, stress and anxiety, mental health problems, and absenteeism due to noise, adversely affect the economy by reducing productivity, increasing healthcare costs, and affecting property values, particularly in urban areas. Noise pollution can deter tourists, and negatively impact tourism and related businesses. Investments in noise control technologies, infrastructure improvements, and public awareness campaigns add to economic costs.
WHITE, PINK, BROWN NOISE: White noise or “broadband noise” is a higher-pitch static sound with a mix of sound frequencies like that from a fan, air conditioner, or vacuum. Drowning out distracting sounds helps some individuals to sleep, focus on their work or study, reduce Attention-deficit/hyperactivity disorder (ADHD) symptoms, and calm crying babies. Pink noise has a lower pitch than white noise and is more relaxing, like a steady rain, wind rustling through trees, or waves on a beach. Some individuals get better sleep with it. Brown or red noise is a rumbling deeper bass-like sound similar to a steady heavy rainfall or a shower with good pressure. Some sleep apps use this sound instead of pink noise. Brown noise or its opposite the higher pitch violet or purple noise may help those with tinnitus(ringing in their ears). Blue noise is shriller than pink and white noise like the hissing noise when a water spray is turned on. Grey noise has higher and lower frequencies but not so much in the middle frequencies.
EARPODS, NOISE CANCELLING
HEADPHONES
Many have taken to sleeping with wireless earbuds for the comfort of soothing music or podcasts. This can lead to sound-induced hearing loss (even if the volume is low); battery safety risks; and the accumulation of earwax and moisture in the ear canal, conducive to ear infections. Noise-cancelling devices use active noise cancellation (ANC) with a built-in microphone that senses ambient noise like jet engine noise, cars honking, and snoring to produce opposite or reversed sound waves to neutralise it. Ambient sound elimination reduces awareness of surroundings, increasing the risk in traffic-like situations. Overusing noise-cancelling headphones can lead to hearing damage, headache, ear pain, dizziness, and disorientation as the absence of ambient sound can disturb our natural sense of balance. Environmental Noise Cancellation (ENC) or Clear Call Quality technology removes ambient noise to ensure the user’s voice clarity in a noisy environment during calls or video conferences.
ACOUSTIC ENGINEERING
Acoustic engineering involves redesigning sound sources, designing noise barriers, sound absorbers, suppressors,
buffer zones, and hearing protection (earmuffs or earplugs). It also covers ultrasound in medicine, speech recognition, programming digital synthesizers, designing concert halls to enhance the sound of orchestras, and public
address systems so that announcements are intelligible. Aeroacoustics is concerned with noise generated by aircraft and wind turbines, and musical notes of wind instruments. Underwater acoustics deals with sonar to locate submerged objects, underwater communication by animals, climate change monitoring, and marine biology.
NOISE REDUCTION:
Better urban planning and road design, measures for uninterrupted traffic flow, and noise barriers and trees can reduce roadway noise. Aircraft noise can be reduced by using quieter jet engines and altering flight paths and timing. Prefabricated building parts can reduce construction noise. Noise mapping and better acoustic engineering of industries and machinery will help reduce noise. Tree planting on roadsides, railway sidings, and around commercial and industrial areas will reduce the spread of noise. Noise regulations need to be implemented by the District Magistrate, the Commissioner of Police, or officers designated by them. Fines and penalties can curb noise pollution. The Mumbai Police launched a novel ‘Honk More, Wait More’ scheme. The wait time is automatically increased if impatient drivers honk at signals. More public action is required by non-governmental organizations such as the Awaaz Foundation, to reduce noise pollution through public education campaigns, creating awareness, advocacy, and public interest litigation. Earplugs or earmuffs, music, and noise-cancelling headphones can help us. We can reduce noise pollution at home and offices by restricting noisy appliance usage, placing sound barriers, shutting doors and windows, and lowering the volume of audio devices.
* Dr P.S.Venkatesh Rao is Consultant Endocrine, Breast & Laparoscopic Surgeon, Bengaluru.