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Scientific news from Division 1 | ||
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Sound insulation screens successfully tested in orchestras |
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After the implementation of the new EU
Directive 2003/10/EG regarding protection against noise at the work
place, a sound insulation screen for orchestra musicians has been
developed in a joint project of WG 1.63 "Noise Measuring Technology",
the Städtische Bühnen Münster und the Accident Insurance
North-Rhine Westphalia. The sound reduction values already determined
in laboratory measurements could now also be confirmed by measurements
performed during an orchestra rehearsal at the Städtische
Bühnen Münster/Westphalia. |
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| For this purpose, a loud passage in the first
movement of Anton Bruckner's 9th symphony was played under four
different conditions which were simultaneously recorded with eight
calibrated microphones and evaluated: 1. without sound insulation screens, 2. with commercially available curved sound insulation screens placed near the head, behind the individual musicians, 3. with flat sound insulation screens manufactured in accordance with information from the musicians in the stage workshop, 4. with the large-area sound insulation screens developed in WG 1.63. Figure 1 shows the measured sound level difference between the values measured with and without screens at different positions in the orchestra (negative values mean a reduction in the acoustic level). It was the objective to keep the high levels of the brasses (trombones and trumpets), which are emitted forward, away from the ears of the woodwind players such as clarinets, oboes and bassoons who are most strongly affected by them. For this purpose, the measurement points were selected near the brasses and the woodwind players, as well as at one point in the center of the orchestra (strings) and close to the conductor. In each case, the mean level value LAeqT was measured over a period of approx. 30 s. At the ears of the woodwind players, values of up to 104 dB(A) were recorded without screens. |
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| Figure 1: Sound reducing
effect of different types of sound insulation screens, measured at
eight positions in the symphony orchestra |
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| The measurement results presented clearly document
that the objective of a level reduction can - in the case of the
woodwind players - be achieved considerably better with the aid of the
PTB screens (with values of up to 12.5 dB) than with the small-area
models so far used. The level increase feared by the brass players as a
result of the screens installed in front of them could not be
confirmed. Even near the conductor and at the measurement point close
to the strings, a reduction by 2 dB was measured, by which the sound
balance during the rehearsal is changed only slightly. The values shown
here are valid for the case that only the brasses are playing. As
expected, the level differences in measurements with the complete
orchestra ("tutti") were lower by 3-6 dB only, as in this case also the
sound generated by the woodwind players is measured. |
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| Contact person: | |||
Ingolf Bork, Dept 1.6, WG 1.63, E-Mail: Ingolf.Bork@ptb.de
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