How Does a Sound Meter Interpret Different Frequency Ranges?

In summary, when using a noise meter, the reading on the dB (A) and dB (C) scales may not add up to the total sound pressure level of 100 dB SPL due to the filter being applied to specific frequency ranges. The dB (C) scale focuses on low frequencies, while the dB (A) scale focuses on a broader range. Therefore, it is possible to have a reading of 60 dB(A) and 90 dB(C) even if the sound hitting the meter is 100 dB SPL. The overall measurement is based on the pressure of the sound, with a reference threshold pressure.
  • #1
fisico30
374
0
Hello Forum,

I am planning to buy a noise meter.
This instrument receives a signal that carries a certain total power. A spectrum analyzer tells us how this total power is distributed among the various frequency components.

When the sound meter gives a reading in the dB (A) scale it is practically applying a filter to that frequency spectrum and giving us the area (power) contained only in those frequencies. For example, if 100 dB SPL of sound hit the noise meter the reading will probably be less dB than 100 because the meter only cares about a certain frequency range...

dB (C) focuses on the low frequencies...

Question: If the meter is in front of a noise source, the dB reading on the dB (C) scale can be larger than the reading on the dB (A) scale. The dB(A) and dB(C) reading don't sum up to 100 dB SPL? why not? For instance, could it be that we read 60 dB(A) and 90 dB(C) even if the sound hitting the meter is 100 dB SPL...
Thanks,
fisico30
 
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  • #2
It is basically a pressure measurement.

Sound power level ##P=20log(\frac{P}{P_{ref}})##

Where Pref is the reference or hearing threshold pressure.
 

Related to How Does a Sound Meter Interpret Different Frequency Ranges?

1. How does a sound meter measure sound?

A sound meter works by measuring the sound pressure level (SPL) in decibels (dB). It has a microphone that converts sound waves into electrical signals, which are then amplified and displayed on a scale calibrated in decibels.

2. What is the difference between a sound meter and a decibel meter?

A sound meter and a decibel meter are essentially the same thing. They both measure sound levels in decibels. Some people use the term "sound meter" to refer to devices that measure all types of sound, while "decibel meter" specifically refers to devices that measure noise levels.

3. How accurate are sound meters?

The accuracy of a sound meter depends on its design and calibration. Most sound meters have a margin of error of +/- 1-2 dB, which is generally acceptable for most applications. However, for more precise measurements, specialized sound meters with higher accuracy may be needed.

4. Can a sound meter measure all types of sound?

Yes, a sound meter can measure all types of sound, including speech, music, and noise. However, some sound meters may be better suited for specific types of sound. For example, a sound meter designed for industrial noise may not be as accurate when measuring music.

5. How can I use a sound meter for noise monitoring?

To use a sound meter for noise monitoring, you should first determine the appropriate measurement location and height. Next, make sure the meter is properly calibrated and set to the correct weighting and time constants. Finally, take multiple measurements over a period of time to get an accurate average sound level.

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