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  1. #1

    Micro phone sensitivity

    what is microphone sensititvity?
    if sensitivity is high? What is the effect?
    if sensitivity is low? What is the effect?

  2. #2
    Camera Operator/Producer lake54's Avatar
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    If the sensitivity is high, the microphone will pick up everything, and if the sound is too loud (e.g. using high sensitivity at a club or if someone shouted down the mic) then you risk blowing parts due to the massive signal.

    Conversely, if the sensitivity is low, you will struggle to pick up small sounds, which may be what you want. However, when you boost the sound afterwards in post-production, doing it by too much may result in a very noisy audio track.

  3. #3
    Spec-wise, sensitivity means how much voltage out per unit of sound in. A low-impedance dynamic mic, with normal speech at a distance of 1 foot, puts out 1 to 3 millivolts. A dynamic mic with neodymium magnets puts out a few dB more, a condenser mic puts out maybe 10 mv.

    The main problem with a low-sensitivity mic is background hiss. You can't get rid of it, as the mic itself generates some. (This is called self-noise.) The lower the output, the more you have to amplify it, and the louder the hiss gets. If you're recording a quiet sound at a distance, this can be a real problem. A good mixer has inputs that are quiet enough that the mic itself, whether dynamic or condenser, is the main source of hiss.

    Ideally, the higher output of a condenser mic should mean that the design of mixer inputs is not as critical. In most cases, the mic's internal preamp is noisier than it needs to be, by as much as 15dB, which means some of the potential of a condenser mic is not realized. Comparison of the self-noise figures of, say, a $2,000 studio mic and some of the Chinese ones will show this difference. Whether or not this is important depends on what you're doing with the mic. For most purposes, the noise of even a $100 Chinese mic is not a problem, and many of them are excellent in every other way.

    The main problem with a high-sensitivity mic is overload on loud sounds. A condenser mic can overload, one of the reasons many drummers prefer dynamic mics. Better condenser mics have built-in sensitivity switches to allow the mic to handle very loud sounds. You wouldn't use the switch except with loud sounds, because it worsens the noise performance by as much as 20dB. Good dynamic mics are hard to overload, but a hot signal can overload the mixer if the input attenuator is not set correctly. A dynamic mic inside a kick drum can put out peaks of 5 volts, which is high even by line level standards.

  4. #4
    The higher the sensitivity, the microphone can pick up the sound from a long distance, is this right ?

  5. #5
    No. Sensitivity is only an "efficiency" rating: how much output voltage will result from a certain sound.

    The main factor that determines how a mic picks up sound at a distance is its directional pattern. Any mic can pick up any sound at any distance. The hard part is to keep that sound from being ruined by other sounds that the mic also picks up at the same time. For distant sounds, choose a microphone with a narrow pickup pattern, like a shotgun mic.

  6. #6
    A microphone sensitivity specification tells how much electrical output (in thousandths of a volt or "millivolts") a microphone produces for a certain sound pressure input (in dB SPL). If two microphones are subjected to the same sound pressure level and one puts out a stronger signal (higher voltage), that microphone is said to have higher sensitivity. However, keep in mind that a higher sensitivity rating does not necessarily make a microphone better than another microphone with a lower sensitivity rating.

  7. #7
    New Member
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    You can't use the same mike for all applications as you know. A singer may use an electromagnetic carbon analog mike. That takes a strong input within 1/2" of the vibrator diaphram. On the other hand, a 'surveillance' type mike will nominally be run through a "VOX" (voice operated switch). When there is no input, the recording device will stop. However, just before that happens, the mike will run wide open and may even pick up a ticking clock in another room. These mikes are called electrit (not a typo). Just a thought. see [url removed due to security threat]
    Last edited by lake54; 21st Dec 2010 at 19:36. Reason: URL Removal

  8. #8
    Yeah, If the sensitivity is high mic will pick everything and it also causes hardness for the microphone, normally it should be adjusted in the middle and don't disturb it, then that will be fine.

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