# how to convert SPL in dBA to dB

I wonder how I can convert dBA (A weighted) to dB and vice versa. can anybody provide any kind of table or online conversion app? thanks

following formula comes from https://en.wikipedia.org/wiki/A-weighting :\begin{align} R_A(f) &= {12194^2 f^4 \over \left(f^2 + 20.6^2\right)\ \sqrt{\left(f^2 + 107.7^2\right)\left(f^2 + 737.9^2\right)}\ \left(f^2 + 12194^2\right)}\ ,\\[3pt] A(f) &= 20\log_{10}\left(R_A(f)\right) - 20\log_{10}\left(R_A(1000)\right) \\ &\approx 20\log_{10}\left(R_A(f)\right) + 2.00 \end{align} how can I inverse this formula? I also must mention that I have a specific frequency and I just want to convert this specific frequency SPL

• this has nothing to do with filter-design,kalman-filters, digital, and only kind of something with filters. Feb 22, 2021 at 13:47
• Do you have a single SPL value, or SPl values for the whole spectrum? Feb 22, 2021 at 18:37
• @Justme. just single value Feb 27, 2021 at 19:48
• @ali if you have a single value, and no information about the frequencies present in the signal, it cannot be known how it is converted between unweighted and A-weighted values, as it depends on the frequencies present in the signal. Feb 27, 2021 at 20:04
• @ali Why did you not say earlier then, that detail is important and should be edited in the question. The formula gives you the weight at any frequency. So if you have a single frequency, you can calculate the weight at that single frequency. And since you know the weighted value and how much the value was weighted, you can also know what was the unweighted value. Feb 27, 2021 at 20:21