1.	Introduction

Noise is one of the most important man-made environmental nuisances, which causes significant disturbances and health problems. In Germany, more than one person in two feels disturbed by noise. What annoys them most is road traffic noise; noise caused by neighbours as well as aircraft and industrial noise also play a major role. Figure 1/1 gives the results of a representative survey from 2010 on the dimension of noise pollution.

People living in city districts near the centre are particularly exposed to traffic noise. Many keep their windows closed most of the time or even all of the time or do not use their balconies or terraces. Restrictions like these are considered as a substantial limitation of a person’s indoor environment quality.

Figure 1/2 shows the noise exposure of Stuttgart's population to road traffic (Noise mapping City of Stuttgart 2012). We see that 19 % of the population is exposed to a day-evening-night level of L_DEN > 55 dB(A) and 12 % to a night level of L_Night > 50 dB(A) from road traffic alone.

Figure 1/3 (Noise mapping City of Stuttgart 2012) gives an overview of the noise exposure of Stuttgart's population to all examined sources of noise.

Among other things, noise can provoke communication disturbances, a lack of concentration, sleeping disorders, headaches, inappetence, aggression as well as a decline in a person’s physical and mental working capacity.

Noise can also have negative health effects, depending not only on the noise level but also on the length of the exposure. A permanent and long-term exposure to noise levels of about 60 to 65 dB(A), which is common along major roads, may lead to cardiovascular problems, a high blood pressure and sometimes even a heart attack and death. People who are exposed to high levels as from about 85 dB(A) for a short time can suffer a temporary shift of their threshold of hearing and a traumatizing of the hair cells in their inner ear. The time to recover from these damages is about 16 to 48 hours. A longer exposure to levels higher than 85 dB(A) or a shorter exposure to levels of more than 100 dB(A) lead to an irreversible damage of the hair cells, which cannot be cured even through medical treatment.

Noise pollution causes significant economic costs as well. The amount of these costs, which are mostly not paid by those causing the noise, cannot always be quantified. But they must still be taken into account when deliberating about noise abatement measures.

Such costs are caused by the medical treatment of noise-induced diseases, accidents after a noise-induced lack of concentration or a loss of production due to the temporary or permanent absence of affected staff members for example.

Besides the costs for negative health effects, there are also costs resulting from lower rents and property sale incomes. Studies on rent defaults give an average value of 0.9 % loss per dB(A) beginning with 50 dB(A). Rent losses of 19 million euros per year and property value losses totalling 1,550 million euros (Federal States’ Immission Control Committee LAI 2012, p. 65) have been determined for the noise-exposed roads of the city of Berlin.

Reduced property prices and falling rent incomes have negative effects on the municipalities' tax revenues as well, which are among others fed by rent incomes, real estate transfer taxes and real estate taxes.

The Indications for noise abatement plans (LAI 2012, p. 15) list "noise damage costs" per resident and year for daytime levels from 55 dB(A).

The huge economic costs clarify the importance of noise prevention and noise abatement aspects already in the planning phase.