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So I have a pair of Bose noise-cancellation headphones that I plug into my keyboard every night to charge them (via my keyboard's USB port). My keyboard happens to be a metallic Apple keyboard. You will see why this may be important to note later.

Over time, I noticed a certain dull, electrical buzzing sound in my right earbud which occurred when I turned the noise-cancellation on. This buzzing sound was not constantly there. It would randomly appear for arbitrary periods of time and then vanish. It wasn't loud either, but it was loud enough to be noticeable and annoying.

For the longest time, I had no clue why this would happen. Sometimes the earbud would be perfectly silent (as it's supposed to be)... and then a buzzing noise would come out of nowhere. This was incredibly annoying and my only remedy was to listen to loud electronic music which blended in with the buzz and made it relatively unnoticeable. Of course, listening to almost any other kind of music proved annoying since my earbud would randomly, intermittently buzz at me.

Finally, one day, I noticed that when I touched my Android phone, the buzzing sound would increase in volume. I thought at first that this was due to my bodily position somehow stretching the wire, but with further testing I confirmed that my Android phone was the culprit. I slowly discovered that touching different objects, even when the headphones were not plugged into the speakers, would result in volume changes of this buzz.

One thing I noticed was that touching the headphone jack, whilst touching the Android phone that increased volume, would silence the buzz. With further testing, I noticed that touching my metallic keyboard would also silence the buzz, even whilst touching the Android phone or under any other circumstance in which there was a buzz.

I finally realized that my body is somehow conducting electricity when touching objects such as my Apple keyboard, headphone jack, or Android phone and that these are all related to the annoying buzz and nullification thereof. I found this bizarre and fascinating.

Ever since this discovery, I've found that I can silence this annoying buzz by pressing any of my fingertips on my metallic keyboard. This is also annoying, since it can make typing awkward to continually have one finger pressing against the metallic part. Nonetheless, I have no idea why this works at all; I suspect it might have something to do with my usage of the keyboard to charge the headphones via its USB port every night, but I have no substantiation of this hypothesis.

So my question is twofold:

  1. How does this bizarre phenomenon work wherein my body is apparently conducting electricity from objects which somehow control some anomalous buzz in my headphones?
  2. And how can I make this buzzing sound stop without keeping my body in contact with those objects? Obviously, I can't hold the headphone jack and listen to anything at the same time, and this habit of touching the metallic part of my keyboard is not great for typing nor my wrists which already suffer from CTS.

Any insight is appreciated.

GDP2
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    How is the mains earth situation in your home? Any of these appliances connected to it? – Jeroen3 Nov 21 '18 at 08:32
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    +1 for "loud electronic music" as a "solution" – Jasen Слава Україні Nov 21 '18 at 10:14
  • don't measure for conductivity, measure for capacitance.. (at least the human body isn't able to generate enough magnetic inductance to affect the electronics). – kagali-san Nov 21 '18 at 13:14
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    I think this question would be improved by editing it for brevity. The story of how you discovered the symptoms of the problem just adds lots of extra reading. All that's needed is "My problem is X. It gets better if I do Y and worse if I do Z. What causes this and how can I fix it?" – David Richerby Nov 21 '18 at 16:03
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    The inconvenience of having to continuously touch the metallic part of your keyboard could be mitigated by using an antistatic wristband and attaching the wristband's roach clip to your keyboard. EDIT: Damn, already suggested. – Vikki Nov 21 '18 at 18:16
  • That's actually quite a common issue with Bose(R) Acoustic Noise Cancelling(R) headphones. Some suggest that the battery might be worn out and that it should be replaces (I **guess** that would be after one or two years of ownership), others suggest that the headphones should be replaced. And, yes, it has also been mentioned that you should not listen to soft music on these headphones because of the noise the Acoustic Noise Cancelling(R) generates. – Klaws Nov 22 '18 at 10:00
  • Clearly you are supplying Apple electrons which are incompatible with all non-apple devices. Try giving it some android electrons – Darren H Nov 22 '18 at 12:49
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    Dupe : [Bose QC20 in-ear headphones 50Hz buzzing noise on PC](https://electronics.stackexchange.com/q/407443/50736) – J... Nov 22 '18 at 13:00
  • Does it pay better than a bus conductor? – Sridhar Sarnobat Nov 22 '18 at 17:15
  • Your first solution was probably the best one: if there is an offensive noises, bring in a louder noises that is even more offensive. The Bose noise canceling headphones are an excellent product. I use mine at Starbucks to cancell their politically correct “music”. – richard1941 Nov 23 '18 at 16:09

5 Answers5

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The "buzz" is almost certainly RF pickup. This can be the mains (low frequency, 50/60/100/120Hz, unlikely in this scenario given a phone is involved) or rectification of the carrier frequency of the phone - remember how old tape players would make a "duh duh, duh duh" sound whenever a text message is received.

Human bodies are conductive. When your skin is dry you are about 100kOhm to 1MOhm. When your skin is wet, that goes down to about 10kOhm to 100kOhm. So there is nothing unusual about becoming a conductor.

As to why touching a metal keyboard kills the hum, or even touching the headphones jack. Basically as you are a nice large conductive area. When connected either to earth (e.g. via the keyboard shell and PC) or to the ground of the phone (e.g. headphones jack), you are basically changing how your body is interacting with the electric fields around you.

EMI is a dark art - it's hard to say exactly what current path you are interrupting, or how you are interacting with the fields. But generally if you ground yourself it stops you acting as an antenna - sort of like shorting yourself out.

One simple option you could try is to buy an anti-static wristband. That would allow yourself to be connected to earth (or to your keyboard) without having to touch the keyboard. Alternatively you could try simply charging your phone from something other than your keyboard to see if that stops noise injection.

Tom Carpenter
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    ESD wristbands have 1 Megohm resistor between the user and ground. Such a weak pulldown probably won't improve EMI issues very much. –  Nov 21 '18 at 15:22
  • @Wossname: Given that it wouldn't be being used for any actual taking apart of electronic devices, it shouldn't be much of a problem to bypass said resistor. – Vikki Nov 21 '18 at 18:18
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    @Sean I think there is a potential safety issue with connecting yourself directly to ground. I think the resistor is important for safety. – Wayne Conrad Nov 21 '18 at 19:47
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    @WayneConrad: Even in the kinds of situations ESD wristbands are intended for (i.e., _not_ taking apart power supplies or the like), there isn't anywhere near enough charge separation to hurt you even if it suddenly discharges all at once; the resistor is to keep it from hurting _the computer you're working on_. Electronic components are a LOT more sensitive to ESD than people are. And in the present situation, given that he isn't getting shocked when he touches his (presumably grounded) keyboard _directly_, he shouldn't be in any danger from bypassing the resistor. – Vikki Nov 21 '18 at 22:37
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    @Sean My understanding is that the resistor is there in case you came into contact with line current somehow. Which is more likely when you're working on electronics than when working on a computer, so my point is somewhat moot. – Wayne Conrad Nov 21 '18 at 22:56
  • @WayneConrad: If you're working on electronics without depowering them first, you are either terminally stupid or have a death wish. And if you're at risk of coming into contact with line current by touching your keyboard, something is very, very wrong with the keyboard. – Vikki Nov 21 '18 at 22:59
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    @Sean You are over-generalizing. There are occasions where you _have_ to work on "live" devices. Yes, even AC line-powered ones. Troubleshooting a not-powered device can be next to impossible. So can many types of adjustments. Correct bench practice is to power the device under test from either an isolation transformer or a GFCI / RCD. – Jamie Hanrahan Nov 22 '18 at 03:03
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    Aside from that... you're both correct. The 1 Mohm resistor in an anti-ESD wrist strap is there to avoid _both_ very rapid static discharge and hazard from electric shock. – Jamie Hanrahan Nov 22 '18 at 03:07
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The main fact, in my opinion, is that noise is heard only in right channel.

First thing comes to mind is issue with grounding. But then both channels would receive the noise.

Second - the source of this noise. You must try another headphones to see if noise is caused by headphones or is emitted by the source device.

Third, reposition your phone to the left (if it is on the right) to see if the noise moves into left bud.

Generally I think you will come to the conclusion that something is wrong with right channel of the headphones and headphones are faulty (as the right wire "picks up the RF" as Tom said in his answer, and then amplifies this signal when you turn noise cancellation on, but left does not).

Anonymous
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My guess is that there is a break in the insulation of the right earbud and that electrical hum from your body is flowing into the noise cancellation amplifier.

Try wrapping the bud in cling film and see if that stops the buzz.

Jasen Слава Україні
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If you have a multimeter available, you can put it into AC voltage measurement mode and try to measure between the different metallic objects. Note that you should only touch the objects with the probe, not with your skin when measuring. For example, touch one probe to the keyboard and other probe to some metal part on the phone.

If you find a ~60 volt (for 120VAC countries) or ~120 volt (for 240VAC countries) voltage between the objects, it is most likely due to ground potential in the devices. Many mains-powered devices nowadays are designed without a ground wire, and RF filtering capacitors inside the device will leak a small amount of electricity. This becomes apparent when you are between a grounded and an ungrounded object.

These issues can usually be solved by placing a galvanic isolator between the headphones and the computer. You can search for "3.5mm audio isolator" to find suitable devices.

jpa
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This is a really lame workaround to the buzzing noise, but if you're desperate...

Skin Contact via USB Charge cord

Comments on Tom's answer re: grounding straps not working, led me to this (one weird trick that all buzzing noise Bose owners should know :P).

With the USB charge cord attached on the Bose end (the USB micro-b end), take the USB-A end of the cord and keep it in contact with your skin.

How you do that is up to your imagination.

(Stick it in your waistband, trapped under your armpit, taped to your forehead, chained to your ankle like a 20kg metal ball, etc.)

Baker
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  • Safety note: Be aware that this provides a direct connection between your body and the wall socket (via the computer). This will normally be earthed ground, however, if anything goes wrong (you have a bad wiring in the building, or your power supply fails in a bad way), you **will** get shocked. Moreover, attaching such a wire in ways and places you described will make it impossible for you to drop it quickly. – akwky Jun 11 '21 at 11:31