9. Adjust the Avg. Power Cutoff slider (in the Transfer Function Controls window) so that the pointer is in the middle. This will allow you to get an accurate time delay calculation. 

10. Click the Compute Delay button. The Delay Finder will appear and automatically compensate for the acoustic delay. 

11. Adjust the Avg. Power Cutoff slider (in the Transfer Function Controls window) so that the pointer is near the left hand end of the slider. This will help the MBM thresholding system reject environmental noise. If the traces are not moving at all, select Age from the Fade pop-up menu. Ensure that the traces are flashing bright green all over the entire audio bandwidth. If they are not, decrease the Avg. Power Cutoff slider until the traces start flashing. (You do not want the trace to be completely bright green – just flashing).

12. Adjust the Avg. Rate slider so the pointer is near the middle of the slider. This will cause the Transfer Function to average over a reasonable period of time.

Avg. Rate Slider – You use this slider to control the averaging rate of the transfer function analysis. The far left end of the slider is “No averaging” and the far right end of the slider corresponds to averaging over 2 minutes (approximately). The averaging done by the transfer function is a decaying exponential average, so it is difficult to assign a numerical value to the averaging rate. In general, acoustic systems require a larger averaging rate than electronic systems. If you use music for the test signal you need a larger averaging rate than if you use noise. 

Avg. Power Cutoff Slider – You use this slider to control threshold level applied to the spectrum of the source signal. When the source signal level is higher than the threshold (this is computed for every spectral line in the spectrum) the transfer function adds the measurement to the average. If the level is below the threshold, the data is ignored. You can see which bands are above the threshold level by setting the Fade pop-up menu to Age. For every band that is above threshold, the response curves will be drawn in bright green. For normal acoustic testing, you want the response curves to be flashing on and off – not a constant bright green and not a constant dark green. This allows the MBM thresholding to reject environmental noise the best.