Noise – An Insidious and Subtle Threat

“Blindness separates people from things;
deafness separates people from people.”
― Helen Keller (American activist, author and lecturer)

Hearing is an incredible process by which the ear transforms sound waves (vibrations) in the external environment into nerve impulses (electrical) that are conveyed to the brain, where they are interpreted as sounds. Hearing is essential for communication, personal safety and for experiencing our surroundings. It helps us to develop intelligence, understanding and emotions. Hearing provides us with an amazing ability to identify and comprehend the most minuscule acoustic cues. Hearing, along with vision, is very important for our survival. However, we often take this sense for granted and expose ourselves to circumstances that can impair it permanently.

Noise implies ‘unwanted sound’ or ‘sound that is loud, unpleasant or unexpected’. Commonly, sound, which pleases the listeners, is termed music, and that which causes pain and annoyance is termed noise. Sound is such a common part of everyday life that we rarely appreciate all its functions. Apart from enabling communication, it helps us to relax e.g. Music, it can alarm us e.g. Fire alarm and even allows doctors to diagnose disease states e.g. Heart murmurs. However, at times, what is music for some can be noise for others. Noise is a form of waste energy. The effect of noise on human health depends on both, loudness and frequency. Noise is described in terms of loudness (intensity) and pitch (frequency) and noise exposure is measured using a logarithmic decibel (dB) scale. Any source producing sound levels of more than 80 to 90 dB for more than eight hours is harmful to human ear.

Humans are provided with a pair of ears, and each ear can be divided into three parts-outer,middle and inner. The outer ear consisting of the auricle and the ear canal is separated fromthe middle ear by the ear drum. Auricle collects sound and sends it through the ear canal toreach the ear drum. The middle ear is an air-filled cavity containing three bones (ossicles)-malleus, incus and stapes. These bones form a bridge and transmit the vibrations from the eardrum to the inner ear. A narrow tube – Eustachian tube, connects the middle ear to the backof the nose. It is responsible for equalizing the pressure between the air outside the ear andthat within the middle ear. The inner ear contains a coiled tubecalled the cochlea. The vibrations make waves in the fluid of the cochlea. These wavesproduce electrical impulses which travel along the auditory nerve to the brain.

Hearing loss is termed conductive when it results from dysfunction of any component of thesound conduction system, i.e., the ear canal or the middle ear (the eardrum or ossicularchain), or both. E.g. impacted wax and infection. Sensorineural hearing loss is caused bydamage to the structures in our inner ear or auditory nerve. E.g. noise injury and ototoxicmedicines. Sometimes it may be a combination of both (mixed hearing loss). Hearingimpairment is classified as mild, moderate, moderately severe, severe and profound. Thosewith mild impairment have no problem in quiet but may have real difficulty followingconversation in noise. Profound impairment results in inability to hear and understand even ashouted voice whether in quiet or noise.
Noise pollution is the result of modern industrialized urban life with poor urban planning and congestion due to over population.

Industries like Textile mills, printing presses, engineering establishments (metal works) etc. contribute heavily towards noise pollution. The list of vehicles causing noise pollution is endless. Increasing vehicular traffic has given rise to traffic jams and the repeated hooting of horns by impatient drivers contributes to noise pollution. Indoor sources of noise pollution include gadgets like the mixer-grinders, pressure cookers, vacuum cleaners, sewing and washing machines. Entertainment equipment in the house like the radio, music players and television sets contribute significantly to noise. Construction site noise especially late night and on weekends can harm nearby residents.

Even the rural areas are affected by noise pollution due to the use of Tractors, Thrashers, Harvesters, and Powered Tillers etc. The wider spread of a 24-hour society has led to increase in noise pollution. In the context of hospitals, external noise includes traffic and sirens whileInternal noise includes ventilator noise and alarms, heart monitor alarms, telephones ringing, trolleynoises, talking (staff, nurses), visitors, fellow patients, and general activities.

Vulnerable groups of people who are most affected by noise pollution include children, elderly, and the hospitalized. Even foetuses are affected by noise pollution when their mothers are exposed. Some studies suggest that exposure to excessive noise during pregnancy, may result in high-frequency hearing loss in newborns and may be associated with an increased risk of growth retardation.

Hearing loss in children leads to impaired speech and language development, delayedcognitive functions, social isolation and learning problems that result in reduced academicachievement. Adults with hearing loss suffer from depression, social withdrawal, cognitivedecline and difficulties in securing employment. Unfortunately, the majority of people withhearing loss live in low- and middle-income countries and do not have access to interventions.
Noise pollution has adverse effects not only on hearing but on general health of humans as well. Constant exposure to loud noise not only causes hearing loss but also reduces our sensitivity to sounds. There may be ringing in the ears (tinnitus). In fact, many young adults experience sudden onset tinnitus or impaired hearing after exposure to loud music at concerts. Studies have linked aggressive behaviour, disturbance of sleep, constant stress, fatigue and hypertension (high blood pressure) to excessive noise levels. Industrial workers regularly exposed to high noise levels are found to complain of nausea, headaches, argumentativeness, changes in mood and anxiety. Noise pollution impairs task performance at school and at work. It increases incidence of errors and decreases motivation. Reading attention, problem solving, and memory are adversely affected by noise.
Noise pollution damages the animal kingdom by altering the fine-tuned balance between predator and prey detection and avoidance and interfering with the use of sounds in communication, in relation to reproduction and navigation. This in turn damages the plant kingdom as the affected animals can no longer take part in pollination. Man-made noise is disrupting marine life where almost every living creature depends on sound as a primary sense for communicating, mating, hunting, and survival.

Zoning urban areas to maintain aseparation between residential areas and zones of noise (busy roads, industries, and markets) is useful.Trees absorb and dissipate sound energy and thus act as Buffers. Law should be enforced to curbviolations leading to noise pollution. Silence Zones must be created near Schools and hospitals. Indiscriminate use of loudspeakers at public places should be restricted. In addition, askingstaff to modify their behaviour results in a lowering of baseline noise levels in schools, hospitals andoffices. It is well said that “You can’t feel the pollution unless you hate it”. We should beconscious and responsible citizens. Activities like planting trees in our surrounding,playing music atlow volume, blowing horns of our vehicles only if needed, training pets like dogs so that theirunnecessary barking does not contribute to noise and abiding laws meant to prevent noise pollutionare concrete steps to curb the menace of noise.

Noise pollution is a significant public health problem in thepresent times. The ill effects are pervasive and medically significant. Noise isomnipresent in our daily lives, yet it is an unnoticed form of pollution.The prevention of hearing loss and future disability is dependent on the actions taken today. Social stigma remains the biggest obstacle to treating hearing loss. Glasses are in fashion but it is required that hearing aids are also made fashionable. Strong and important characters in movies can be shown using hearing aid instead of simply portraying hearing loss as comical. Health is not an optionbut a necessity and access to health care is not a privilege but a basic human right. Noise is an insidious and subtle threat lurking in our everyday lives. We need to address this before it drowns us out.

ALSO READ: Watchful and Reverent