Noise disturbance is a difficult issue to evaluate as it is open to subjective reactions. Its impact is not a lasting one on the actual environment, but it can have significant adverse effects on people living close to an airport, including: interference with communication, sleep disturbance, annoyance responses, learning acquisition, performance effects and cardiovascular and psycho-physiological effects.
Unless there are very many aircraft following a route, it is widely recognized that aircraft flying at a height of at least 10,000ft above the ground do not usually produce “significant” noise impact. But because of the subjective nature of disturbance and the wide variance of local factors, this is not an absolute rule. It is normal for aircraft noise to be associated with airports, because of the low height involved.