ESDU 94035:2011

This Item provides a computerized 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
the ground impedance and air turbulence. Guidance on the required
values of ground impedance and turbulence parameters is 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
measured data. The possible ways of minimizing ground reflection
effects by the suitable choice of microphone heights are
discussed.

Full documentation for the program, referred to as ESDUpac
A9435, is provided together with an input and output example.

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