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PTB > Structure > Division 1 > Scientific news > Soundfield in front of a specimen in a test stand for walls |
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Deutsche Version |
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Scientific news from division 1 | ||||
| Soundfield in front of a specimen in a test stand
for walls |
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| Measured sound level distribution at a distance of 10 cm from a wall in a test stand at a room resonance (1-2-mode) of f = 108,3 Hz, values of the momentary sound level corresponding to the colour scale (red = positive values, blue = negative values) and scale for the wall axis given in dm. | |||||
When measuring the acoustical properties of partition
walls a sound signal will be generated in the transmitting room inside the test stand and
its diminution will be measured in the receiving room. Applying spacial averaging an
apparently constant distribution of the acoustical excitation is simulated. Even though,
errors in measurement may occur if resonances of the room appear as standing waves, shown
by the analysis of the sound field on the surface of the wall. As we can see on the
distribution of the sound level at a 108 Hz resonance presented in the figure, the uneven
excitation of the wall has to be taken into consideration. The zones between the nodal
lines of the specimen are excited with high level whereas the zones nearby the nodal lines
get lower sound excitation. |
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