FIELD: acoustics.
SUBSTANCE: invention relates to acoustics. The method of compensating for the first and second errors contains a stage at which a probe containing a loudspeaker and a microphone is placed in the acoustic load. The load has an open end and a second closed end. Then an acoustic signal is emitted by a loudspeaker, and the input signal generated by the incident part and the reflected part of the signal propagating through the acoustic load is recorded by the microphone of the acoustic probe. The incident part of the output signal contains a plane-wave part and a part of non-propagating modes. The acoustic impedance is then calculated based on the ratio between the input signal and the output signal, with the acoustic impedance including the first error due to the part of the non-propagating modes from the incident part, and the first error being defined as an approximation using the acoustic mass. Then the initial value of the unknown characteristic impedance of the acoustic load is set; the reflectivity index is calculated based on the ratio between the measured acoustic impedance and the initial value of the unknown characteristic impedance, the error in estimating the reflectivity is calculated from the Hilbert transform of the imaginary part of the reflectivity index, subtracted from the real part of the reflectivity index and added to the imaginary unit multiplied by the inverse Hilbert transform of the real part of the reflectivity index, subtracted from the imaginary unit multiplied by the imaginary part of the reflectivity index. Also calculated are the real part of the error in estimating the reflectivity and the imaginary part of the error in estimating the reflectivity, and the acoustic mass is iteratively adjusted to minimize the imaginary part of the error in estimating the reflectivity.
EFFECT: increased accuracy of the measurements.
10 cl, 13 dwg
