Hi, My centre speaker is not working properly, the sound is dull and dialog not very clear. I would like to measure the spec of this speaker, and, having a SPL meter, I was thinking to use my PC to play some audio file of basics sinewave at different frequency (from 20Hz to 20 Khz) and record the Db level measured as a function of the frequency played. I've made a quick google search of such basic files but can't find any. I'm sure there is no problem of copyright to ask any of you if you knows a website where I can pick such trivial files. Many thanks.