Let's now describe the user parameters related to the FIR filter generation. Note that, every time a
user parameter is changed, the “Calculate FIR” button at the top left of the screen start blinking,
meaning the FIR filter needs to be recalculated. Once the button is clicked the synthesis algorithm
computes the FIR filter with the new parameters and the corresponding plots are updated.
-
Mode
Two different working mode is available:
1) “Magn+Phase”. When this option is selected the FIR filter will compensate both magnitude and
phase of the measured IR. For the magnitude response a target curve can be applied.
2) “Phase only”. In this mode the FIR filter works on the phase response only, leaving the IR
magnitude unchanged.
-
Max Frequency
Before calculating the FIR, the first thing the user should do is to look the frequency response of the
IR, mainly to check the upper cut frequency. This is useful to set the maximum operating frequency
above which the FIR filter will be neuter leaving the original IR unchanged. Moreover, it should be
remarked that:
1) The frequency response at very high frequencies can strongly depend on microphone position,
since the most of audio transducers are very directive in this frequency range. So it is worth to try
different microphone positions moving it of few centimeters, and choosing the one which gives the
best result.
