Pet Peeves of a Pedant: #2

Sometimes, on a rare occasion, I can muster up enough gumption to admit that I’m wrong. This posting is just such an admission… Once-upon-a-time, I learned about equal loudness contours (I will explain these below…). Then I learned about weighting filters and how they’re used to make a measurement system as imperfect as we are. (I will also explain this below). The short explanation at the end of that lesson was “A-weighting is for measuring quiet sounds, and C-weighting is for loud sounds.” This put a hard-and-fast belief in my head that then made me grumpy any time someone published a specification that said something like “maximum sound pressure level: 120 dB SPL (A)”, since 120 dB SPL is NOT a quiet sound – so the idiot that wrote that should have used a C-weighting instead. However, as Bertrand Russell once said, “It’s healthy now and then to hang a question mark on things you’ve long taken for granted.” It turns out that my almost-religious-indignation regarding “mis-” use of…