Environmental Noise (and Vibration) can over a multitude of areas, from Complaints and Compliance to Impact Assessments and Modelling.
The definition of 'noise' as 'unwanted sound' implies that the tolerance of an activity can depend on the perspective - one person's 'sound' is another person's noise in other words.
There are also some potentially significant health effects associated with long-term exposure to elevated noise levels.
Often environmental noise is a comparison of baseline conditions with the noise level of the activity in question e.g. impact assessment for new developments. Various national and international guidance assist the acoustician in a balanced assessment, however, while every effort is made for objective evaluation, there is often scope for interpretation.