PLANNING FOUNDATIONS
2.3 Noise, sound emission and sound immission

Disturbing sound or disturbing noises are termed "noise". This shows that the term "noise" includes a negative assessment of neutral physical terms. According to DIN 1320, noise is audible sound, which disturbs the silence or a desired sound perception or which causes annoyances or adverse health effects. What we have to consider is the subjective character of the term "noise", which is revealed by the fact that the negative impacts of noise on a person are associated with their current situation.

In order to guard against misunderstandings, the differentiation between emitted sound and incoming sound has proved necessary depending on the situation and has become common practice in the field of environmental protection. There is in fact a major difference between the statement that a machine for example emits too much noise (emission) and the statement that this noise exceeds defined noise limit values in the affected neighbourhood as an environmental impact (immission).

A systematic differentiation between the terms "emission" and "immission" is regulated by the Federal Immission Control Act (Bundes-Immissionsschutzgesetz/BImSchG). § 3 of this act gives the following definitions:

(1) "Harmful effects on the environment" as used herein shall mean any immissions which, because of their nature, extent or duration, are likely to cause hazards, significant disadvantages or significant nuisances to the general public or the neighbourhood.

(2) "Immissions" as used herein shall mean any air pollution, noise, vibration, light, heat, radiation and similar effects on the environment which affect human beings, animals and plants, soil, water, the atmosphere as well as cultural objects and other material goods.

(3) "Emissions" as used herein shall mean any air pollution, noise, vibration, light, heat, radiation and similar phenomena originating from an installation.

Exceeding a particular acceptable extent, immissions are called "harmful effects on the environment". The occurrence of an immission implies a previous emission.

In technical acoustics, the term "emission" designates the process of the emission of sound waves from a source and their entering the environment.

An immission lies therefore at the end of a causal chain with an emission at the beginning. The link between emission and immission is "transmission" (propagation), which usually weakens the environmental effects on the propagation path from the source of the emission to the place of reception (point of immission) due to the distance and local conditions.

The official use of the terms "emission" and "immission" requires the context of human actions, with the consequence that the associated effects on the environment are man-made. This means that the twittering of birds, the breaking of waves and the howling of a storm for example are not considered as noise within the meaning of the Federal Immission Control Act. In principle, this circumstance is easy to understand but it can cause certain problems in real life when it comes to sound measurements and the assessment of complaints as the question of where nature ends and a causer (emitter) comes into play can sometimes be controversial. These disputes range from the keeping of animals (e.g. cock-crows or the croaking of frogs from a garden pond) to the noise of running waters (in the context of hydraulic-engineering measures) or to the sound of wind (in the context of tower blocks and overhead lines). It therefore proves necessary at this point to refer to the term "installations" used within the Federal Immission Control Act and described below in section 2.1.1.

The causal chain of emission – transmission – immission (see fig. 2/2) plays an important role in the context of noise reduction as each of the three components can be the subject of noise reduction measures. For this purpose, an extensive set of technical regulations is available, which is under constant development and revision.

A selection of guidelines and directives:

In the following chapters, we will go into more detail about particular guidelines and ordinances as far as it is necessary in the context of this Noise Manual for Urban Development. Particularly regulations on the last-mentioned category are of significance for city planning.