by Bart Kosko. PhD, 2006. .252 pp. Viking-Penguin, publisher.
Much of this book is technical in nature. However, some of the information may be both useful and interesting to the general public. Some extracts and notes by Alice Fedorenko are presented below.
Noise is a by-product of modern life.
Unwanted noise may be divided into two categories – private nuisance and public nuisance. Noise is a private nuisance if it substantially and unreasonably interferes with someone else's use and enjoyment of their land or other real property (home, apartment, etc.). That is, an indirect trespass is committed since someone else's land is affected without the owner's permission; for example, if a neighbour frequently plays his stereo very loudly.
On the other hand, noise is a public nuisance if it substantially interferes with a right common to the public; for example, where a local airport or a noisy bar substantially interferes with the public's use and enjoyment of their land or property. Both the private and public forms of noise nuisance may be difficult to resolve due to different personal interpretations, "fuzzy definitions" and judicial balancing that may result in possibly unjust settlements. Such outcomes have spawned social activism, including environmental movements and local community protests over new land development.
The overall noise will only get worse as cities expand and more people use more gadgets. We already know that noise may lead to serious health concerns as humans respond to the ever increasing decibel-levels and signal complexity by experiencing sleep problems, increased stress, and even increased risks of heart attacks and high blood pressure. Some of the harmful effects of noise are detailed below.
Noise and hearing loss
Noise can lead to hearing loss. The extent of hearing loss is governed by how much and for how long the noise energy impinges on the inner ear – sufficient noise energy can readily damage the delicate inner part of the human ear. According to a 1998 medical article, about 15% of American teenagers have permanent ear damage, likely due to listening to amplified music. Noise-induced hearing loss, known as NIHL, is a serious and widespread concern in working environments, and one of the most common occupational illnesses. According to the US National Institute for Occupational Safety and Health, some 30 million Americans are reportedly exposed to NIHL noise hazards in their workplace, and of these, about 10 million have permanently damaged hearing. With the escalating noise levels, the reported hearing problems for people aged 14 to 44 have increased by 26% between 1971 and 1990.
The human ear and auditory cortex can detect and process a wide range of sound intensities, including a whisper (10 decibels) and a rocket engine (180 decibels), with the threshold of pain for most people observed at about 120-130 decibels. However, hearing loss can also occur at non-painful decibel levels if the noise-exposure is sufficiently long. For example, two straight hours of 90-decibel noise can cause permanent hearing loss – a risk faced by many factory workers. Loud music is a particularly common risk of noise-induced hearing loss for baby boomers and musicians, as one minute exposure to about 130 decibels (at a rock-concert stage) may result in some hearing loss.
Noise-induced stress and sleep deprivation
Noise can cause stress. As the human world "evolves" towards more and more machinery and gadgetry (aircraft, cars, appliances, powerful car stereo speakers, numerous other personal electronic devices, etc.), an increasing number of people are experiencing noise-induced stress. Where noise disrupts or prevents sleep, a variety of health problems may arize – from increased blood pressure to decreased immune response.
C. Mashke (Biological Effects of Noise) states that intermittent noise is one of the most frequent causes of sleep disorder. Such noise can cause awakening, forcing the sleeping person to repeatedly restart the sleep cycle, which requires energy. Intermittent noise can also disrupt sleep even if the individual does not awaken, by producing fundamental changes in the sleep structure, including fragmentation of the sleep process, reduction of REM (rapid eye movement) sleep, disturbance of mental /emotional processes and extension of the shallow sleep period. In densely populated areas, explosive bursts of noise in the night may affect huge numbers of slumbering people. For example, based on the European Union's 3-dimensional noise maps, "A single noisy motor scooter driving through Paris in the middle of the night can wake up as many as 200,000 people" (Newsweek article, April 2004).
Noise and the inner ear
Good hearing depends on the health of the about 16,000 hair cells present in each inner ear. An energy signal travels as a sound wave from the noise source to the vibrating eardrum, through fluid canals back up the curled-up cochlea in the inner ear. There the hair cells reside and act as frequency detectors. If damaged, these hair cells do not regenerate, and their permanent loss is the leading cause of deafness. For example, when loud noise bends or breaks the fine hairs in the inner ear, the specific frequencies normally detected by these (now damaged) hairs cannot be picked up, resulting in partial deafness. Damage to the hair cells may also result in false electrical signals causing the persistent ringing of tinnitus.
A single loud noise impulse may result in permanent deafness if the blast occurs sufficiently close to an unprotected ear – for example, a single blast from a handgun or shotgun, a powerful firecracker explosion, or even the penetrating roar of a motorcycle where the ear is too close to the muffler. Even less energetic noise blasts may lead to severe noise-induced hearing loss if the sound lasts long enough. For this reason, those who wear headsets should turn down the volume, or not wear headsets at all.
One contentious area is the possible harm due to excessive cell-phone use. A Swedish study reported in 2004 that the use of cell phones could result in damaged hearing. In their hypothesis, the faint energy signals manufactured in the cell phones were linked to potential chromosomal mutations of a particular gene, possibly leading to an increased risk of growing benign tumors on the acoustic nerve. This apparent finding applied only to those cell-phone users where an analog cell phone was used for at least 10 years (fewer years of use did not produce detectable results; also digital cell phones were not tested as sufficient long-term data were not available). Whether or not the use of cell phones increases the risk of tumors should be clarified conclusively once the longer-term data are available from the ever increasing numbers of cell-phone users.
Despite the complexity of noise signals and noise pollution, the first step in combating the harmful effects of noise is to understand how our bodies respond to it. Additionally, the development of accurate and quantitative measurements of noise should empower us to address this far-reaching problem more effectively.
An article in Nature (Feb 2004) describes the European Union as the world leader in visually quantifying the various noise levels in urban environments. This was done by producing three-dimensional contour maps of the cities, where color codes denote the different decimal-based noise levels. These maps are useful for developers and politicians, and allow the public to see at a glance which areas are quieter (more livable) and which show benefits from contentious noise-control measures, such as stricter traffic regulations. As well, the decibel-based maps provide the public and the legislators with a more effective tool when seeking to reduce specific sources of noise. Yet anther essential component in fighting noise pollution is to regularly modify city's noise-zoning laws to keep pace with the ever changing technology that constantly brings in new forms of noise pollution.