FxLMS updates the adaptive filter using a reference signal filtered by the secondary path. A larger step size speeds convergence, but delay and long filters reduce stability margin.
How to read it
The waveform view shows how the anti-noise signal cancels the primary tone.
The convergence plot reveals where a larger step becomes oscillatory.
The spectrum view checks whether the target tone drops without raising nearby bands.
Learn Active Noise Control FXLMS by dialogue
🙋
When reading Active Noise Control FXLMS, where should I look first? Moving Target frequency changes both the plots and the result cards.
🎓
Start with Estimated attenuation, but do not treat the number as the whole answer. Use Cancellation waveform to confirm the assumed state, then read FxLMS convergence for the distribution or trend. The waveform view shows how the anti-noise signal cancels the primary tone.
🙋
I can see why Target frequency changes Estimated attenuation. How should I judge the influence of Original noise level?
🎓
Move Original noise level in small steps and watch Residual noise. That reveals which term is controlling the result. FxLMS updates the adaptive filter using a reference signal filtered by the secondary path. A larger step size speeds convergence, but delay and long filters reduce stability margin. A single operating point is not enough; sweep the realistic scatter range.
🙋
What is Residual spectrum for? It feels like the ordinary curve already tells the story.
🎓
Residual spectrum is for finding boundaries where the condition becomes risky or margin collapses quickly. The convergence plot reveals where a larger step becomes oscillatory. In First-pass studies for duct or tonal machine noise, the important question is often what happens after a small change, not only the nominal value.
🙋
So if Estimated attenuation is within the target, can I accept the condition?
🎓
Treat this as a first-pass review. It helps with Initial tuning of adaptive-filter length and step size and Checking stability margin when secondary-path delay is large, but final decisions still need standards, measured data, detailed analysis, and vendor limits. The spectrum view checks whether the target tone drops without raising nearby bands.
Practical use
First-pass studies for duct or tonal machine noise.
Initial tuning of adaptive-filter length and step size.
Checking stability margin when secondary-path delay is large.
FAQ
Start with Estimated attenuation and Residual noise. Then use Cancellation waveform to confirm the assumed state and FxLMS convergence to read distribution or bias. The waveform view shows how the anti-noise signal cancels the primary tone
Move Target frequency alone, then move Original noise level by a comparable amount and compare the change in Estimated attenuation. Residual spectrum shows combinations where margin or performance changes quickly.
Use it for First-pass studies for duct or tonal machine noise. Instead of trusting a single point, widen the input range and check whether Estimated attenuation keeps enough margin before moving to detailed analysis.
FxLMS updates the adaptive filter using a reference signal filtered by the secondary path. A larger step size speeds convergence, but delay and long filters reduce stability margin. Final decisions still require standards, measured data, detailed analysis, and vendor limits.