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At 12:14 PM 9/30/2014, DAVID BURNHAM wrote: > I have not experienced nor can I imagine why a trombone would have > negative spikes. The only explanation I can think of is that the > absolute polarity of the microphone has been reversed, but that would > affect trumpets as well. The query that started this thread was about a live recording made in the 1970's. When I first started doing live sound work in 1970, I built a device which measured polarity of microphones, because I understood that it was important that the mics all have the same polarity. When I first measured the several dozen mics in our collection, the results were 60% pin 2 + and 40% pin 3 +. There was no standard for which polarity was correct -- it varied from one manufacturer to another, and even in some cases over time with a single manufacturer. And, I doubt that polarity was checked in manufacturing test, because one day a recording company showed up with a brand new matched pair of Neumann mics, and we found that they had opposite polarity. Oops! Thus, I would not be at all surprised to find that different instruments in a 1970's recording have different polarities. > As far as why a woman's voice would have higher spikes than a man's > voice, my explanation, (which everybody is welcome to argue with), is > that every human voice, male and female, has the same amount of high > frequency energy - mainly consonants. But a male voice has much more low > frequency energy which might tend to mask some of the high frequencies, > especially if he's close to a mike which might lop off the spikes. I've done enough dialog editing to know that a few male voices are quite asymmetrical. Broadcasters discovered asymmetrical voice waveforms long ago. For those interested in audio history, Google "Kahn Symettra-Peak" to read about a device patented in 1959 which claimed to fix this problem. -- John Chester