This is good to know. I've never used the Peak or Impulse measurements, only the Fast option. This could explain why I've had spikes when I felt I shouldn't have, based on the decibel reading.
I also struggle to make sense of any dBC measurements, as I'm not sure what the thresholds for those are, since all of the readings are typically much higher than dBA. So I know I'm missing valuable information by only using dBA, but it's just what I'm accustomed to.
I can summarize what I have learned quite briefly. It is always good to know, in case someone reads this in the future.
Most decibel meters use either FAST or SLOW measurements, like I mentioned earlier. These are great for measuring things like a concert, standing next to a highway, or other types of fairly constant noise over time. For sudden sounds, such as a door slam, a gunshot, dropping something on the floor, or fireworks, they are kind of useless.
Let us say that the peak sound of dropping a phone on the floor is 115 dBC for 12.5 ms, and you are using FAST. In practice, the meter will only show an averaged value. Roughly speaking, it becomes something like (115 × 1 + surrounding sound × 9) divided by 10. If the surrounding sound level is, for example, 50 dBC, the display would theoretically show about 56.5 dBC. In reality, there is usually some rattling or reverberation after those 12.5 ms, so the meter might show something closer to 75 dBC.
So, dBC is basically just a more unfiltered version of dBA, right?
With dBA, you are filtering out frequencies that are considered less harmful to the human ear, such as very low frequencies, and keeping the higher frequencies that are more likely to damage the hair cells inside the cochlea. For example, if you have 80 dB at 100 Hz, a dBA measurement applies a reduction to that value before showing it on the display. You might see something like minus 20 dB at 100 Hz, minus 15 dB at 250 Hz, minus 9 dB at 500 Hz, and so on. These numbers are just illustrative.
dBC does not apply that reduction. It simply shows the decibel level being received.
A typical situation with a lot of low frequencies would be being outside in a city environment, with a highway a few miles away. On a dBA reading, you might get around 40 dB, while on a dBC reading you might get closer to 50 dB. This happens because the dBA measurement slightly reduces those lower frequencies that are generally less harmful to our ears.
I am not entirely sure, to be honest. Constantly measuring in dBC can be somewhat confusing, I think.
And if anyone notices that I am wrong about something, please let me know. I do not want to give out false information.
