Sound level meters have different scales. We use the dBA scale because: It weights those frequencies that the human ear is most sensitive to and the thus gives in indication of the effect of the noise on the ear of the hearer It weights those frequencies about 20,000 Hz to and the thus gives in indication of the effect of the noise on the ear of the hearer It weights those frequencies that are above 10,000 Hz and the thus gives in indication of the effect of the noise on the ear of the hearer It provides a uniform weighting and the thus gives in indication of the effect of the noise on the ear of the hearer