noise pollution Flashcards
Noise Pollution
wikipedia: noise is unwanted sound that is considered unpleasant, loud or disruptive to hearing.
according to physics- noise is indistinguishable from sound
difference arises when the brain receives and perceives the sound, classifying as unpleasant and disruptive.
Human hearing and sound
normal range of human hearing is said to be about 20 Hz to 20kHz (20 cycles per second to 20,000 cycles per second)
babies hearing higher frequencies and as we age we lose the ability to hear at an upper end of the range (presbycusis)
age related hearing loss- changes in the inner ear or middle ear, changes along the nerve pathways from the ear to the brain, certain medical conditions, use of medicines and noise-induced hearing loss.
How we hear
sound enter outer ear and travel through the ear canal to the eardrum
eardrum vibrates and sends these vibrations to 3 tiny bones in the middle ear (malleus, incus and stapes)
bones convert vibration in the air to fluid vibrations in the cochlea of the inner ear and set up a travelling wave along the basilar membrane
sensory hair cells on top of this membrane ride the wave and bumpy tiny projections against an overlying structure- causing them to bend- opens pores, flushing chemicals into the cells, creating an electrical signal
auditory nerve carries this electrical signal to the brain- we interpret as sound
Wavelength and frequency
wavelength = speed of wave / frequency
Why noise matters to us?
major environmental issues to humans
impacts both physical and mental health
linked with sleep disturbance, annoyance, decrease in cognitive performance, increased risk of preterm birth, anxiety and depression, hearing loss and tinnitus, hypertension and various cardiovascular disease
Why noise matters to other species?
noise disrupts natural signalling in birds and frogs
call rates, frequency and amplitude may be affected
may also cause same harm as in humans
Current European legislation
Within Europe, the 2002/49/EC Environmental Noise Directive (END) was formulated to provide a common European Union approach to assessing exposure to environmental noise within Member States.
under the END, Member States are required to produce strategic noise maps for the assessment an d management of noose exposure for all majors roads, railways, airports and urban agglomerations
Problems with current noise mapping
environmental noise only takes into account emitted by certain means of transport.
methods used are based on propagation models, using annual traffic flows data from roads, railways and aircraft-no established method to do this-different countries use different algorithms.
Reducing noise pollution
remove the source- legal measures such as vehicles, construction sites, factories, speed limits etc.
engineering solutions- low noise road surfaces, engine properties, separation of dwelling from roads.
masking solutions- distractions such as water fountains, flowers
Summary
cities are noisy places with an increasing urban population- more people at risk of mental and physical harm
noise from vehicles often goes hand in hand with air pollution
should be aware of the dangers from all parts of the sound spectrum
impacts on biodiversity are poorly known but clearly disruptive
urgent need for the identification and protection of tranquil spaces.
