IEC Acoustic Standard IEC 61400-11
IEC Acoustic Standard IEC 61400-11
IEC Acoustic Standard IEC 61400-11
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6 Instrumentation<br />
Microphone & preamplifier<br />
Size, diameter no larger than 13mm<br />
Measurement board<br />
Circular with diameter of at least 1m<br />
Made with acoustically hard material like plywood with<br />
thickness 12mm or metal with 2.5mm. A larger board is<br />
recommended for soft ground.<br />
Primary microphone windscreen<br />
One half of an open cell foam sphere with diameter of 90mm<br />
Secondary microphone windscreen<br />
Sold but expensive<br />
Example – wire frame hemispherical shape 450mm<br />
diameter covered with 13-25mm layer of open cell foam<br />
NATIONAL RENEWABLE ENERGY LABORATORY<br />
8
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