Sound Engineer Question - Weighted A or C to check noise in Prius?

Discussion in 'Gen 2 Prius Accessories & Modifications' started by Free One, Apr 6, 2007.

  1. Free One

    Free One New Member

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    I picked up a Radio Shack Sound Level Meter to see if I can objectively track changes in my Prius's road noise level as I continue to add sound deadening.

    I noticed that when I use the "Weighted A" setting (the freq response range of A is 500 - 10,000 Hz) for measuring the sound level, it's not too bad: 73 db or so as I drive up I-5 with my current configuration of sound deadening, while the same stretch of road measured in the "Weighted C" freq response range (32-10,000 Hz) comes in around 92 db, which is a huge jump.

    My questions:
    How much am I really "hearing" in the 32-500 db range that seems to be so much louder?
    Which weighting is best if I want to measure the kind of noise that creates more fatigue?
    What kind of sound deadening works best for the "percievably loudest" part of the spectrum in my measurements?

    Thanks!
     
    #1 Free One, Apr 6, 2007
  2. KMO

    KMO Senior Member

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    If you're measuring noise to see how it impacts on humans, use A weighting. That's what's used when measuring noise pollution, or whatever. It applies weighting to indicate how loud it seems to humans.

    If you're trying to calibrate audio equipment levels, you use C weighting.

    I suspect C is showing higher because of lots of very low frequency rumble, which humans don't perceive that well. For your purposes, you want to compare A readouts.
     
    #2 KMO, Apr 6, 2007
  3. lenjack

    lenjack Active Member

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    Yes..."A" corresponds more to the way we hear.
     
    #3 lenjack, Apr 6, 2007
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