Does my iPhone hate my Sennheiser noise cancelling headphones?

August 7, 2007 8:45 AM

My iPhone and my Sennheiser noise cancelling headphones are not playing nicely. Periodically, I get an annoying buzzing/interference noise when I'm listening to music on my iPhone and have noise cancellation switched on.

My equipment:

Brand new iPhone
Older Sennheiser noise reducing headphones, PXC 250 model
Belkin iPhone adapter

I live in NYC. I sometimes get this interference while at my desk at work. I also consistently get this noise when waiting for the train, on the subway platform. It happens 100% of the time when an oncoming subway train is approaching. If an express train passes my station, I hear a horrible, loud buzzing sound for several seconds until the train passes.

My gut reaction is that it has to do with the iPhone searching for a cellular signal. Can I make the buzzing stop?

posted by kathryn to technology (11 comments total)

Is it this?

http://ask.metafilter.com/26557/can-you-hear-your-cell-phone-signal
posted by crickets at 8:50 AM on August 7, 2007

Yeah, what crickets said. GSM signal.
posted by awesomebrad at 8:52 AM on August 7, 2007

Yuck.

I do get it a lot when I'm not receiving calls, though.

What I don't understand is why it would always happen when a subway train is coming my way.

Is there anyway to make it stop and still be able to use the noise cancellation on my headphones?
posted by kathryn at 9:05 AM on August 7, 2007

I have the PXC 300 model. I find that if I keep my phone on one side of my body and the noise reduction unit on the other side then it removes almost all of the phone interference. Is there any way you can increase the distance between the phone and the NR unit when listening to music?

If you are desperate enough to pay for a new set then I recommend the PXC 300's as one of their selling points is better shielding from mobile phone signals.
posted by urban greeting at 9:29 AM on August 7, 2007

Do you have another mp3 player / ipod you can test the headphones on in the same environs? You need to first isolate that it doesn't have anything to do with the phone itself. I'm guessing, based on your description and the fact that the model you are using has active noise canceling, that its more a matter of the headphone getting overwhelmed with extremely loud noises, and you're hearing some sort of feedback because of it.

If you're able to test them and find out that this is indeed the case, you may want to consider passive noise canceling headphones - I have Shure's E4C's and I love them.
posted by allkindsoftime at 9:29 AM on August 7, 2007

I'll second the passive headphones - both Etymotic and Shure make excellent sounding earbuds with something like 23-30db of noise cancellation.

Also I think Shure makes a little microphone you can use to convert the headphones into a talk headset for use with the iPhone...
posted by roygbv at 9:42 AM on August 7, 2007

I do get it a lot when I'm not receiving calls, though.

Just to reinforce the argument that this is your GSM signal, I used to get this type of interference right before phone calls, but now I find that it happens all the time - that is, at random, at least in terms of what I am doing with the phone.
posted by phaedon at 10:11 AM on August 7, 2007

I have an iPod nano and never experienced this problem until I got an iPhone. I've also successfully used it to listen to music using the headphone jack on a laptop. I'm fairly certain it's not the headphones.

urban greeting, I'm going to try to put the iPhone on one side of me and the noise cancelling unit on the other side. Hope this works! Unfortunately, this solution won't work all that well on the subway as I usually put both inside of my purse.
posted by kathryn at 10:30 AM on August 7, 2007

I've had this problem with my car stereo cassette adapter and my iPhone, and a friend said he had the same problem with his iPhone and his noise canceling headphones.

I tried switching it to airplane mode, which should turn off all the radios in the device. I still have the problem.

I've been wondering if some sort of RF choke would help, but I haven't tried it yet.
posted by Good Brain at 12:11 PM on August 7, 2007

The noise cancellation circuit has to take the minuscule signal from the outer microphones, amplify it, then feed it phase-reversed to the speakers in order to cancel out the noise. That amplification step also amplifies whatever noise is present on the microphones' wires.

The phone is a radio transmitter, that much is obvious. The trains power themselves from the electrified third rail, and to pull power from that rail, they use a sliding contact which unavoidably sparks as it goes along. That turns every train into a big spark-gap transmitter. Either source of noise will cause problems for unshielded devices.

And of course, the wires leading from the earcup-mounted microphones down to the noise-canceling circuit aren't shielded. That would've made them even more expensive.
posted by Myself at 1:13 AM on August 8, 2007

Turn your phone into Airplane mode if you want to cancel the interference, BUT not receive calls. Not a total fix but will stop the buzzing.

-Ry
posted by rydogg at 11:07 AM on May 12