What did we mean by NOISE??It is unwanted sound that can cause annoyance, sleep disturbance, speechinterference, distraction and at extreme levels,Method commonly used to quantifyenvironmental sounds consists ofevaluating all the frequencies of asound in accordance with a weighingthat reflects the facts that humanhearing is less sensitive at lowfrequencies and extremely highfrequencies than in the mid-rangefrequencies.Aircraft noise is a significant and criticalcomponent of the aviation globaleconomic infrastructure. If there is tobe growth in aviation, theenvironmental impacts of aviation mustbe mitigated.Different aircraft types have different noise levels andfrequencies.The noise originates from three main sources:• Aerodynamic noise: arises from the airflowaround the aircraft fuselage and control surfaces.This type of noise increases with aircraft speedand also at low altitudes due to the density of theair.• Engine and other mechanical noise:Helicopter noise mechanically induced noise fromthe main gearbox and various transmission chains.The mechanical sources produce narrow band highintensity peaks relating to the rotational speedand movement of the moving parts.DWELLINGS Day?time• Indoors the dwelling during the day/evening – 35 dB LAeq 16 hour• Outdoor living areas – 55 dB LAeq 16 hour to protect the majority of people frombeing ‘seriously annoyed’ during the day-time.• Outdoor living areas – 50 dB LAeq 16 hour to protect the majority of people frombeing ‘moderately annoyed’ during the day-timeNight?time• Outside facades of the living spaces should not exceed 45 dB LAeq 8 hour and 60 dB LAmax toprotect from sleep disturbance.• Inside bedrooms – 30 dB LAeq 8 hour and 45 dB LAmax for single sound events to protect fromsleep disturbance.SCHOOLS & PRE?SCHOOL• School playgrounds outdoors should not exceed 55 dB LAeq during play to protect fromannoyance.• School classrooms should not exceed 35 dB LAeq during class to protect from speech intelligibilityand, disturbance of information extraction.• The reverberation time in the classroom should be about 0.6 s.• Pre-school bedrooms – 30 dB during sleeping time & 45 dB LAmax for singlesound events to protect from sleep disturbance.Higher systolic & diastolic blood pressureo Elevated neuroendocrine & cardiovascularo Stress related illnesseso Physiological effectso DepressionAcoustically-rated windows;o Solid-core wood entry doors (known as prime doors);o Replacement of sliding glass doors;o Solid wood baffle air conditioner covers;o Acoustically-rated storm doors; ando Thermally-glazed windows in non-living spaces.o Window modifications;o Addition of acoustical insulation batts to ceiling assemblies;o Weather-stripping windows and doors;o Installation of new air conditioning and ventilation systemso Addition of vestibules at exterior doors.Placing down regulatory constraints on the amount of noise generatedby aircrafts and flight paths.2. Rejecting planning permission where noise levels exceed 66dB at daytimeand 57 dB at nighttime.3. Technical adjustments to thrusts, angle of takeoff/decent, speed ofaircraft, etc…Seek control of scale ofnoise impact, mitigateremaining impacts andprovide compensation:o Offer households assistancewith costs of relocatingo Offer acoustic/soundinsulation to be installedIncentive and penalty system toencourage airlines to use quietaircrafts.o Minimum heights for decent.o Use if flight routes and runawaysthat impose less noise on nearbybuildings.o Noise quotas for nighttime.o Shielding nearby buildingsthrough airport design (buildingsor bunds).Through insulation (whether installed through a grant orpersonal funds):o Sound Insulationo Double-glazingo ETC…The International Organization for Standardization has establishedrestrictive guidelines relating types of land use to airport sound level.1. . All land uses within the areas below 65 dB are considered to be compatible withairport operations.2. Residential land uses are generally incompatible with noise levels above 65dB.3. Above 75 dB, schools, hospitals, nursing homes and places of worship are consideredto be incompatible land uses.