Lmax which is a measure of the loudest part of a flight.There are a number of decibel metrics by which aircraft noise is often described: Knowing the scale of noise is only one element of capturing its impact, it is also important to consider how we measure the impact of an individual event. The most common measure of this is the A-weighted sound level known as dBA. Therefore the decibel unit used to express human response to loudness or annoyance includes a weighting that varies with both intensity and frequency.

Noise measurement also needs to take account of the varying response of the human ear to different frequencies of sound with most sensitivity occurring at the 2-4 kHz range. This relates sound intensity to the smallest audible sound of 0dB, so a sound 10 times more powerful is 10dB, whilst a sound 100 times more powerful than the threshold of hearing is 20dB. To measure this the decibel scale (dB) is used, which encapsulates the energy of sound with reference to the threshold of hearing using a logarithmic scale. The human ear can handle an enormous range of sound levels. Weather can also affect where aircraft are in the sky since aircraft take-off and land into the wind, affecting which runways are used. The weather which can increase or decrease the experience of noise depending on conditions.Whether aircraft are arriving or departing which can affect the amount of engine thrust they are using (and therefore the noise level) and the amount of air resistance around the fuselage, wings and undercarriage.Whether aircraft are directly overhead or how far they are laterally displaced from the receiver (in any direction).How high aircraft are above the ground.The noise level of aircraft can vary immensely depending on a number of factors The level of annoyance also varies owing to factors such as the length of time a person lives in an area affected by aircraft noise, personal sensitivity, the impact of outside influences and the activity the individual is engaged in at the time e.g. But noise is not always just about decibels the pitch, vibration, variation in intensity and the length of exposure time can have impacts too. The way that people experience noise from all types of sources can significantly differ. However as traffic continues to grow as demand for air travel increases, this improvement is often counteracted by the number of aircraft overflying an area. Aircraft noise is caused by airflow around the aircraft fuselage and wings as well as noise from the engines, with different aircraft producing different noise levels and different noise frequencies and tones.Īircraft are individually less noisy than in previous generations with a reduction of noise by more than 90% since jet aircraft entered service in the 1960s.

Noise is defined as unwanted sound that may result in disturbance and annoyance. That’s why we work with airports, airlines and communities to help shape and inform options to better manage the effect of noise and minimise the impacts wherever possible. At NATS we are very aware of the impact that aircraft noise has on those who live under flight paths.

Jet engine decibel