![]() "I turned it down 6 dB" or "that pre gives 60 dB of gain". You have to know the reference level for dB to mean anything.ĭB by itself is only used when talking about a change in level. With the K-20 Metering system you set your levels so that -20 dBFS RMS equals 83 dB SPL. Since analog usually has 'headroom' you calibrate so that -20 dBFS equals 0 dBu on your analog meter-depending on the headroom of course. ![]() ![]() When you interface digital gear with analog, you want to calibrate levels. That's why you sometimes get positive and negative values for dB-it all depends on the reference level. So when you're at the clipping point you get 0 dBFS and you go down from there. In the case of dBFS, the reference is 'full scale' which, in digital, is the clipping point of the converter. 0002 microbar you get 0 dB SPL, and it usually goes up from there. In the case of dB SPL, when the measurement equals. And when the measurement equals that standardized level you get 0 dB-in-whatever-scale. dB scales are always in reference to some standardized level. "dB" all by itself doesn't really have a meaning. ex: Jet plane 100mĭB (used in audio measurement) = How much louder a sound is when compaired to the threshold of human hearing. EDIT : or note the distance to the sound in the results. Remember that for any of your results to be valid the sounds must be recorded with the same mic at the same distance to the sounds. Now leave the mic gain alone, (put gaffer tape over it) and all your recordings/test will be relative to your loudest example. Just start with the loudest sound you're expecting to test and set the sound card input gain, (or portable recorder mic gain) to show Full Scale. The decibel will tell you how much louder or quieter one sound is when compaired to another, it will NOT tell you the precise volume of a sound (although you could work that out)įor the purpose of the school work, dBFS would give perfectly usefull results, is readily available in Sonar and can be calibrated easily. The important part to note (to impress teacher) is that the decibel unit is a comparative measure, NOT an absolute. DBFS = how much quieter a sound is compaired to a sound that would make your equipment read full scale.ĭB (used in audio measurement) = How much louder a sound is when compaired to the threshold of human hearing.
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