Calculation of acoustic

Calculation of acoustic power is based on measurement of sound pressure level and reverberation time of the testing room. Because it is necessary to measure the level of sound pressure, a low level of a background noise is an essential requirement to be able to offer the best testing results. To achieve this, the reverberation rooms are isolated from the surroundings by a double wall. The first wall is of a heavy construction, so an optimum isolation is ensured against aerial noise. The second wall (interior of the reverberant rooms) not only improves the isolation by providing more mass to the construction; its design also gives rise to a very wide sound field (an essential condition for the correct calculation of the sound power level from the sound pressure level).
First, an enclosure was built to form the perimeter of the exterior rooms. Then the inner walls of the reverberation rooms were raised to favour the diffusion conditions in the sound field. Between both structures, an acoustic insulation material was installed; see Figure 1.

1000 inhabitants).

1000 inhabitants). Sales in other European countries are less than 0.1 heat pumps per 1000 inhabitants.
In 2001, of the total sales in Europe of 41,000 ground-coupled heat pump systems, 27,000 were installed in Sweden. For the next 3-5 years, market growth rates have been estimated by industry as shown in Table 2.
Table 2: Ground-coupled heat pump market Europe.
Country Sales 2001 Growth, %
Austria 4,800 8 Czech Republic 350 25 Denmark 150 >100 Finland 1,250 10 France 850 10 Germany 3,600 20 Netherlands 400 >25 Norway 650 10 Poland 500 5 Sweden 27,000 6 Switzerland 2,800 6 UK 150 >100