Active Noise Cancellation - From Modeling to Real-Time Prototyping
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- čas přidán 4. 08. 2019
- Active noise control (ANC), also known as active noise cancellation, attempts to cancel unwanted sound using destructive interference. ANC systems use adaptive digital filtering to synthesize a sound wave with the same amplitude as the unwanted signal, but with inverted phase.
This video first reviews the basic principles of ANC. It then shows how to use Simulink® to design and simulate an ANC system to cancel noise within a pipe model using a Filtered-X NLMS adaptive filter. Finally, you’ll see how to implement the ANC system using a real-world duct pipe and a Speedgoat real-time audio machine equipped with an ultra-low latency operating system and ultra-low latency A/D and D/A converters. The video shows how you can use automatic C code generation to go from the simulation model to the real-time prototype.
Explore the example used in this video: bit.ly/31bTp9z
Other Resources
Adaptive Filters: bit.ly/339uGor
Presentation by ASK Industries at MATLAB EXPO 2018: bit.ly/2KgwIvD
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In conclusion : Noise cancelling is not easy!
Excellent lecture
Back in 2013 I proposed a model like this to folks attending a small hacker space called Hacksburg in Blacksburg, VA. At the time I was being annoyed by people who were apparently set on disturbing my peace so the idea was in fact motivated by a real life problem. 😄 I thought the best approach would be an array surrounding a space. After researching further, a combination of an anechoic chamber with standard shop head phones, surrounded by a speaker system and actuators to conduct into the walls would probably yield the best results. You also have to account for heat and humidity because the filter you have could be thwarted with a hairdryer.
Edited to add:
Apparently a lighter gas than air like helium or hydrogen also helps a lot. The effect there is the inability of the gas to transfer much of the noise, and be easier to maintain than a vacuum as an outer layer of the chamber.
What’s exactly anechoic chamber? Is it not too big, to be installed easily on the headphones, which you will wear in public!?!😂
@@ndeutsch So that's the chamber you go into in recording studios, or places that offer hearing tests. There are materials on the wall to absorb the mechanical energy of the propagating sound waves which then gets turned into heat. Pulling a vacuum around a space eliminates sound thoroughly as it simply has no medium to propagate in. The speaker system would work to actively cancel the waves before they even approach this proposed space which should help theoretically.
The speed of sound also changes with the temperature of the medium the waves travel in. Active noise cancellation can be negatively effected with a device to alternate temperatures such as a hair drier if the circuit doesn't have the time to convert and output the inverted wave patterns before they get there or if they don't line up perfectly to interfere destructively.
This is probably more information than you asked for. 😄
Where I can buy the noise cancelling devices?
Very nice. Thanks!
I got lost at minute three. Not audiologist or IT person or anything. But great words for sci-fi lol. Seems to me metaphorical of "the struggle" trying something so hard, failing, trying again, fine tuning, and then... nah it might fail but at least you gave everything and the effect is noticeable
Hello i m a northafrican student ( Future engineer ) . I have chosen actif noise control as a subject of study . I must realise an experience ( Real world ) then analyse results theoretically .. I like this sumilation model and i hope of being provided with ideas of experiences .. Thank you !!
Does anyone know what type of microphones they are using? How does the mic interface with MatLab?
Does your tech have any application for small outside generators?
Everything he mentioned is valid only for his little fabricated tube scenario. For an arbitrary envrioment, this is not feasible as countless factors play in. Many scams are based on claims of noise cancellation.
FPGA architecture of adaline Apative Fir filter is there ???
Noise cancellation is very simple just take two of the same signals & reverse the phase on 1, instant silence.
Good morning
A question, 2 sample latency is impressive at 8kHz, does it scale with higher sample rates? In other words do you maintain 2 samples latency at higher sample rates or the equivalent time, which would be 4 samples at 16 kHz, 12 at 48 kHz, 24 at 96 etc. Either way the latency is impressive
2 samples are due to double buffering. Mlab did not need any exotic boxes, a [EVM for] DSP would suffice. What they miss is DAC/ADC anti-aliasing filters. They also disregard non-band-limitedness of sensing mic to error mic acoustic path. So they will run into troubles with the non-casual spreading of IR estimate, etc. Adaptive control is not easy, and any attempt to represent it as trivial is profoundly misleading.
noise cancellation systems
inverse of the noise source
PVC pipe ... model
error mic
reference mic .... propagation of noise
Mrs Surya p
h.r
g.m
chairman
aarupadai veedu institute of technology
vinayaka mission university , Chennai
thiruvarur ..
so what happens when you move the microphone?
all hell breaks loose
thats the interesting part, you dont;