# Difference between A and C graphs



## ludwignew (Nov 14, 2008)

When do you have to use C weighting and when A weighting? :dontknow:

I now that this graphs show the ears behavior under different SPL levels. So, what's the main difference in use between this two? :doh:

Thanks!! :yikes:


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## brucek (Apr 11, 2006)

> When do you have to use C weighting and when A weighting?


The A, B, C weighting filters are used to simulate your hearing abilities. The filter to select depends on the sound pressure level, as our hearing changes as sound pressure level changes. Generally, for home theater the C-Weight curve is best and is the only one we compensate for in REW.

brucek


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## Wayne A. Pflughaupt (Apr 13, 2006)

ludwignew said:


> When do you have to use C weighting and when A weighting? :dontknow:


A-weighting rolls off response below 1000 Hz. That is, it filters off or removes bass frequencies from what registers on the meter. A-weighting is commonly used in industrial settings, as the upper frequencies more readily contribute to hearing loss. 

C-weighting adds bass frequencies to what the meter registers, down to ~40 Hz, at which point it begins to roll off. In a typical sound system, particularly a domestic one, that subjectively has linear frequency response, bass levels tend to be higher than the mid and upper frequencies. As such, switching the meter from A to C will result in a higher SPL reading.








Hope this helps.

Regards,
Wayne


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