David, Thanks for your input on this. I understood pretty much correctly, but appreciate your more complete explanation.
By "WAV", yes, I meant linear-coded whatever resolution. I think windoze Sound Recorder records files in this format. They're huge... As a function of my group's charter (at work), we sometimes run distortion analyses on MP3 vs WAV files for plain voice phrasing. They're used in turn-by-turn directions on vehicle navigation units. We'll run the WAV file on the X (ref) axis, and the MP3 on the y axis and snapshot different parts of the phrases with the display on short-term average. We've found differences of up to 10% distortion, though whether it sounds that way to a human ear I have no idea. I suppose it depends on the recording format of the MP3 (resolution again). A 12-bit sample looks the worst - easily naked eye visible. In practice, we use 16-bit sampling at 16 KHz for all non-Text To Speech pronuciations. This seems to work best and whatever distortion there is can't be heard by anyone I've tested. I was only questioning whether or not this would be a valid comparison, and it sounds like MP3 is probably OK for plain voice. Thanks for that answer. 73, matt W6NIA On Sun, 30 Aug 2009 19:30:14 +0100, you wrote: >Matt Zilmer wrote: > >> Does anyone have more input on MP3 vs WAV? > >MP3 has a certain amount in common with noise reduction algorithms, >although what is is trying to reduce is weak sounds so close to the >signal that they won't be heard. With very good noise reduction it may >completely blank noise that was only reduced by the noise reduction. > >Whether it is valid to test noise reduction with a human ear, after the >signal has been MP3 coded, depends on whether or not you believe that >MP3 only removes what cannot be heard, anyway. > >One should never use MP3 on signals that are going to be processed by >something other than a human ear, and I'd personally be wary of using >for any comparison of audio quality. > >By WAV I'm assuming you actually mean 16 bit linear audio, as WAV is a >wrapper format that can wrap MP3. > >Unfortunately, in the same way that JPEG seems to be used for all images >on the web, MP3 tends to be used for all sounds. Both make assumptions >about the nature of the signal and human perception. (PNG is often the >best format for screen shots, for example.) ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
