Do you have anything else plugged in? Do you ever get it without ANYTHING else plugged into the audio or USB port?

Alternator whine is a ground issue. I don't have any in my Sport, but I have the low end radio. It could be something simple as a low quality usb charger...or simply a ground wire not crimped well enough in any of the radio/audio harnesses. It could even be a bad connection/crimp at the battery or alternator.

Maybe a low quality accessory plugged into a 12v receptacle?

 

What model do you have? I test drove a RTL-E last week and I heard the same thing. Sounded like it was coming from the entertainment system/nav. My wife couldn't hear it at first, but she finally heard it as well. I just assumed that there was something wrong with that particular truck, since I hadn't heard it on any of the other models I had driven, but maybe I just wasn't paying attention.

 

Black Edition.

 

Ya know I tried the AM stations today to see if I could hear anything.

Nada.

I do have the base color radio in a RT if it makes a difference.

 

I have alternator whine in my 06 pretty bad. Stock radio with a GROM BT unit. I blame it on the BT unit so far. It is being thrown away in the next week for a new headunit cause it works when it wants to,its 6 ish yrs old. Im not sure why and when the whine started though. If it still does it after the head unit install then I will track it down and check all my motor to chassis grounds.

 

I have a 2017 E Model experiencing intermittent noise when listening to AM. I would describe it as low roaring sound. Honda dealer replaced dash wiring harness with one with more shielding. That did not resolve issue. They did discover that the interference only occurred when passing under high voltage power lines. I have confirmed this. Dealer has notified Honda of issue and "cause"

 

I have a consistent whine that only comes from my tweeters on my RTL-T. It is present when the engine is off or running and doesn't get louder with acceleration or turning the volume up. It is really annoying and my wife's 2017 Pilot doesn't have that issue at all.

 

Those are 2 really critical distinctions Zombie: If engine not running, it's not alternator or coil whine. If it doesn't change with volume it's coming through another path.

I'm curious if the ANC on your Ridge is having a problem... if you're feelin' handy, it might be worth disconnecting ANC to see if that does the trick: http://www.ridgelineownersclub.com/forums/161-2g-audio-bluetooth-electronics-navigation/157730-anc-disable-how-remove-glovebox.html

 

I tried disabling ANC and it had no effect on the hiss from the tweeters. I'm really getting frustrated with this. Any other ideas that I can try?

 

Aww that sucks. Noises like that would drive me crazy too! Since it doesn't change with volume, and isn't the ANC, that points back to some form of induction. If you installed any aftermarket stuff (radar detector, dashcam, etc...), de-power those. Also try removing cell phones and garage remotes for testing. Could also go park it somewhere else to see if that changes the noise (I.e. Away from high current lines). Is the noise really in both tweeters, or just one? If the loop noise doesn't go away with something easy like that, I'm thinking you'll have to trust the dealer under warranty or shell out money for a good car audio guy with experience. (Fingers crossed for ya)

 

The noise from both tweeters happens wherever I am and I don't have a garage door opener in the car, I use homelink. I should clarify that I swapped the factory tweeters for Polk tweeters and had to cut the factory wiring since Crutchfield didn't have a factory adapter.
I soldered the speaker wires and wrapped them in electrical tape and wrapped the included wired in crossover in electrical tape over the included rubber cover. I tried moving the crossover further away frI'm the tweeter but it had no effect.
I live in a small town so I wonder how good the local stereo guys can be if I need to pay for them to solve this for me.

 

I've been hearing a coil whine-like noise. I couldn't figure out where is was coming from. Today I put my ear on all speakers and found that both the driver and passenger door speakers make the sound. Other speakers have a normal light hiss, but these two have a high pitched buzzing noise.

I think it's the amp. I found it in passenger side kick plate (under glove box). Anyone know if it's easy to replace?