Coffeehouse Thread

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Microphone buzz

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  • User profile image
    Sven Groot

    Can anybody explain to me how it's possible that I get the same, highly annoying, buzz in the background on two different computers, with three different soundcards, and two different microphones?

  • User profile image
    Minh

    What does the buzz sound like? Post it. My cell phone creates a very distinct buzz when it's turned on & near my mic. Maybe some other interference.

  • User profile image
    Sven Groot
  • User profile image
    W3bbo

    Sven Groot wrote:


    I could only hear it when I turned my speakers up.

    If its consistent accross all platforms, its probably something in the room. Do you have strip lighting?

  • User profile image
    Sven Groot

    W3bbo wrote:
    Sven Groot wrote: http://www.liacs.nl/~sgroot/buzz.wav

    Bad, innit?


    I could only hear it when I turned my speakers up.

    It's enough to seriously affect the performance of speech recognition. There's only two things turned on in here right now, and that's the computer and the fridge. And I tried on my laptop with the desktop turned off, so that's not it.

  • User profile image
    W3bbo

    Sven Groot wrote:
    It's enough to seriously affect the performance of speech recognition. There's only two things turned on in here right now, and that's the computer and the fridge. And I tried on my laptop with the desktop turned off, so that's not it.


    Then by the process of elimination we can blame the fridge Smiley

  • User profile image
    Sven Groot

    I'll try a few different locations with the laptop later on, see if it's something in the room or if just the whole building is at fault.

  • User profile image
    W3bbo

    Sven Groot wrote:
    I'll try a few different locations with the laptop later on, see if it's something in the room or if just the whole building is at fault.


    Nuoes! The space aliens with their evil oscillating mind-control rays will find you if you go outside!

  • User profile image
    Minh

    The wave form is very regular



    So, I doubt if that's just background noise. Probably some sort of electronic interference. Maybe your monitor? Try turning the monitor off then record.

  • User profile image
    kevinsch

    Hearkening back to my days of being an engineer in a radio station...

    A large fraction of audio buzz in sound systems is caused by what's called "ground loop." The theory of grounding is that by connecting compnents to the ground, you establish a common "zero" across all components -- if you test across any two points on any of your ground cables, you should get zero voltage.

    It's a nice theory, but in practice since there is resistance in all wires (and in the ground), there's always some amount of voltage difference through the grounding system, and if alternating current leaks into it, you get a buzz. The fact that the buzz you're hearing is in the 50-60 Hz range is a very good indicator that you have a ground loop problem.

    If it is indeed a ground loop problem, that would require:

    1. two electrical devices, both grounded (e.g. plugged into the house mains by means of a 3-prong plug). You could get this by having a PC and separately powered speakers.

    2. The electrical devices are interconnected (e.g. your poswered speakers are plugged into the audio card in your PC).

    3. something is leaking AC current into the ground wire. This could be the power supply from either piece of equipment, another faulty component inside the PC, or (unlikely) even another electrical device nearly plugged into the mains (like your fridge, or your stereo).

    Ground loops are notoriously difficult to isolate. So here are some things to try:

    1. Disconnect your speakers from the PC (and from the mains, if powered) and try listening to your PC audio through a pair of headphones. If the buzz is gone, you just found your loop. That doesn't mean that the speakers are necessarily the problem, it just means that they are part of the loop.

    2. Disconnect every non-essential peripheral from your PC, including your printer and particularly everything that has separate power.

    3. leave your computer going with audio playing (so you can hear the buzz) then walk around and unplug appliances one at a time until the buzz goes away.

    4. If desperation is setting in, go to a hardware store and buy an adapter that turns your 3-prong plug into a 2-prong (groundless) plug. Try using it BRIEFLY on your computer to see if it makes the buzz go away. Be aware that it is potentially dangerous to run your computer without proper grounding, so you do this at your own risk and this is NOT a long-term solution -- just a diagnostic tool.

    If none of this works, post something here again and we cain brainstorm some other ideas.

  • User profile image
    Sven Groot

    Interesting, however, I think it's unlikely considering I also hear the buzz on a laptop even when it isn't plugged into the mains. I've tried walking around a bit with the laptop, trying to record at different locations, including the hallway and the staircase, and the buzz doesn't change.

  • User profile image
    NeoTOM

    Mic boost in Volume Control?

    /haven't listened

  • User profile image
    Sven Groot

    NeoTOM wrote:
    Mic boost in Volume Control?

    /haven't listened

    It happens both when it's on or off.

  • User profile image
    W3bbo

    This is really spooky.

    Have you tried a Feng-Shuei consultant? Maybe there's some "bad energy" around you Wink

  • User profile image
    Dr. Shim

    Do all your PCs have an integrated sound chip, or are they all PCI cards? Audio chips on the motherboard produce a strange buzz.

  • User profile image
    W3bbo

    Dr. Shim wrote:
    Do all your PCs have an integrated sound chip, or are they all PCI cards? Audio chips on the motherboard produce a strange buzz.


    I don't know about you... but even with my speakers on full-blast, I can't hear a thing, even though I've got an integrated sound chipset. (AC97)

  • User profile image
    Sven Groot

    The buzz is not on the audio output, only on the microphone recording. It also doesn't happen if the microphone isn't plugged in.

    One of the cards is a Sound Blaster Audigy2 (PCI card), the other two are integrated AC97 chips.

  • User profile image
    Shaded

    Sven Groot wrote:
    The buzz is not on the audio output, only on the microphone recording. It also doesn't happen if the microphone isn't plugged in.

    One of the cards is a Sound Blaster Audigy2 (PCI card), the other two are integrated AC97 chips.



    Buy a decent mic

    Believe it or dont... low power speakers work suprisingly well as microphones - so if you plug in a pair of headphones into the mic port you may be suprised on what you can pick up.

    I'm betting they wont give as much noise either.

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