Originally Posted by sqa4life

Here is an excerpt from the 2013 Honda Accord Press Kit, describing the system:

Active Noise Control (ANC) and Active Sound Control (ASC)
Key contributors to the Accord’s quiet, refined interior are Active Noise Control (ANC) and Active Sound Control (ASC). The two systems are comprised of dual overhead microphones, an ANC/ASC electronic processor, and the audio system’s four door-mounted speakers. ASC/ANC operates whenever the Accord is running, even if the audio system is turned off.

ANC is designed to reduce low frequency sound in the cabin caused mainly by the roughness of the road surface. The overhead microphones pick up sound waves and send them to the ANC/ASC processor, which creates and sends a precisely timed "reverse phase" audio signal to a special amplifier. In turn, the amplifier drives the door speakers to cancel the original noise signal.

ASC is a related technology designed to improve the engine sound quality by making the sound pressure level more linear as the engine revs increase. Typically, engine noise doesn’t increase in a linear way with rising revs; instead there can be many resonances that create peaks and valleys in the sound pressure level and an uneven sound. ASC helps smooth out the engine sound by creating a same-phase or reverse-phase sound signal as needed and sending it to the door speakers. Though the system offers benefits from idle to redline, it makes the largest difference in the range between 1000 and 2000 rpm, where it lowers the sound pressure level by approximately 3-dB with an opposite-phase audio signal.

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The following is my posted question and conversation with the tech:

Question:
I would like to add an amplifier and subwoofer to a 2013 Honda Accord sport sedan, while keeping the factory head unit. I'm told that I will experience a low hum when the Active Noise Cancellation (ANC) kicks in.

Is there simply a wire going to the factory head unit that can be cut, or is there some other way to defeat ANC? Thanks!

Country: United States
Make (manufacturer): Honda
Model: Accord
What have you tried so far?: Nothing yet. Vehicle is a 2013 in sport trim.

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Chat:
OnlineMasterTech :
Hello I will be glad to help you with your Honda questions today.
OnlineMasterTech :
Let me take a look at the schematic to see if the ANC can be disabled.
OnlineMasterTech :
You can actually disconnect the Active Noise Control unit which is located behind the center pocket. Let me know if you need anymore help on how to remove the connector.
BiminiRoad :
Where is the center pocket and how do I gain access to it? How can I identify the ANC unit?
OnlineMasterTech :
Let me see if I can get some directions for you.
OnlineMasterTech :
Click here for ANC unit removal
OnlineMasterTech :
Do you have Navigation?
BiminiRoad :
I do not have Navi. Thanks for the diagram, but it says I have to remove Hands Free Link unit first. Are there separate instructions for that?
OnlineMasterTech :
Yes I was getting ready to post those for you.....just needed to know if you have NAVI or not.
OnlineMasterTech :
I will get them right now. Please print these instructions off as I will delete the link when we are finished.
OnlineMasterTech :
Full Size Image
BiminiRoad :
The ANC removal PDF link worked, but the image you posted did not work
OnlineMasterTech :
Click Here for center pocket removal.
OnlineMasterTech :
Click Here for pocket trim removal
BiminiRoad :
Ok, I got all the PDFs, but the Hand Free Link removal I don't have
OnlineMasterTech :
Click Here for HFL removal
OnlineMasterTech :
Ok that should be all of them.
BiminiRoad :
Ok got it. Can you tell if if there will be any negative side affects of the ANC unit being disconnected?
OnlineMasterTech :
Nothing that you will probably notice. You may hear a little more road noise than usual but it will be minimal......especially if you are adding an amp and using the radio frequently.
OnlineMasterTech :
Do you have any other questions for me today?
BiminiRoad :
Ok, but no diagnostic codes should come up, right?
OnlineMasterTech :
No none that I am aware of unless this system has been changed since the 2012 model.
OnlineMasterTech :
I do not see any information in my database that would suggest that a code would be set.
BiminiRoad :
On the pocket trim removal, does this simply pry up with a small, flat tool?
OnlineMasterTech :
Yes you would want to use a plastic trim removal tool to prevent any type of damage to the trim pieces.
OnlineMasterTech :
I like using a plastic paint scraper to remove the panels
BiminiRoad :
Ok. Installation is the reverse of the removal steps, correct? It seems that way.
OnlineMasterTech :
Yes that is correct.
BiminiRoad :
Excellent. Thank you!
OnlineMasterTech :
No problem at all. This new model Accord is a great car and I hope you enjoy it.
BiminiRoad :
Thanks so much. Good day to you.
OnlineMasterTech :
Please remember to rate me at Excellent Service and Thank You for letting me assist you today!
BiminiRoad :
Of course.
OnlineMasterTech :
You have a great day also!
BiminiRoad :


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In summary, here are the steps:

1. Remove the center console side trim
2. Remove the center pocket
3. Remove the navigation switch panel if you have Navi (I don't so I don't have a diagram for that)
4. Remove HandsFreeLink control unit
5. Remove (or simply disconnect) ANC/ASC control unit

Originally Posted by Cruise12

Here are some videos of the issue.

Accord2 - YouTube

1accord - YouTube

Originally Posted by sfrench40

I know this post is really old but I have a 2013 Accord and your issue is the perfect description of my issue. Mine started a few years after buying the car but it is getting worse. Did you ever find a solution/fix for this?