ESDU 94035
The correction of measured noise spectra for the effects of ground reflection.
Abstract:
ESDU 94035 provides a method of estimating the effect of the sound wave reflected from the ground surface on the measured noise signal. Ground-reflection corrections are provided in the form of a difference spectrum between the measured and free-field spectra. The calculation procedure takes into account ground impedance and air turbulence with guidance on appropriate values given for a range of conditions. The program may also be used to correct a measured spectrum, automatically adjusting for any discrepancy between the cancellation frequencies of the predicted and measured spectra. Such discrepancies may arise from atmospheric turbulence, errors in source location or timing errors. An allowance may be made for the characteristics of the filters used to analyse the measured data. Ways of minimising ground-reflection effects by a suitable choice of microphone height is also discussed.
Full documentation for the programs, referred to as ESDUpac A9435 and VIEWpac M9435, is provided together with an input and output example.
Indexed under:
- Acoustic Impedance
- Aircraft Noise
- Atmospheric Effects on Sound
- Ground Reflection Effect on Noise
- Noise
- Noise/sound Propagation
- Sound
- Turbulence Near Ground
Details:
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This Data Item is complemented by the following software:
| Name | Details | ||||
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ESDUpac A9435 |
This program is only available to subscribers. |
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ESDUpac B9435 |
This program is only available to subscribers. |
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M9435 |
This program is only available to subscribers. |