Although the former AQAV Executive Director, Mario Maltese, has been retired for a bit now, you still cannot talk about everyday mundane things without bringing the conversation back to AV.
While texting about the snow hitting New York today, he sent me a picture of the accumulating snow. The reason for that was, he knows I always loved a good “Snow Day” and always looked forward to school and job closings. Somehow you always find a way to get out to play, but it’s impossible to work in the snow!
Anyway, I text back, “I love how everything gets quiet and muffled when it snows.” What do I get in return? And this is verbatim, “Sabines of absorption”, said the electro acoustician”. My response was that “I would have to look that up”. I’m sure many of you may understand that statement, but for the untechnical people like me, I Googled and found the following:
“The Sabine absorption coefficient is the random incidence absorption coefficient deduced from the reverberation time measurement via the. The reverberation time is the time taken for the acoustic energy in an initially steady reverberant sound field to decay by 60 dB” (Morfey, 2001). (I know, there’s an incomplete sentence in there, but that’s what I found.)
My mind read that as “blah, blah, blah, blah, blah! So, I text back, “OR…It gets quiet when it snows” LOL!
His further response to that, and the reason for me writing this at all is, Wallace “Sabine was a famous acoustician. I (Mario) have one of his books from Cornell Press – as part of the Gutenberg Project*. The unit of absorption is named after him. His work in concert and lecture halls is great reading for today’s AV guys (for historic interest) – it’s amazing how he had to measure things in the early 1900’s before the age of the XL2 Analyzers we had in our (AVR and later AQAV) test kits. The salient point is the dramatic improvement in measurement techniques. Measurements needed to be taken at night over days or weeks as compared with the MRPro and the XL2 in the test kits today, taking only seconds.”
I later Googled “Sabine Equation” and came up with this:
If you don’t read the COLLECTED PAPERS ON ACOUSTICS, by Wallace Clement Sabine at least check him out on Wikipedia. Here’s an excerpt:
“Sabine was able to determine, through the experiments, that a definitive relationship exists between the quality of the acoustics, the size of the chamber, and the amount of absorption surface present. He formally defined the reverberation time, which is still the most important characteristic currently in use for gauging the acoustical quality of a room, as number of seconds required for the intensity of the sound to drop from the starting level, by an amount of 60 dB (decibels).”
“By studying various rooms judged acoustically optimal for their intended uses, Sabine determined that acoustically appropriate concert halls had reverberation times of 2-2.25 seconds (with shorter reverberation times, a music hall seems too "dry" to the listener), while optimal lecture hall acoustics featured reverberation times of slightly under 1 second.”
I know that I am no expert or even slightly technical in any way, but I do understand the need for test kits, and I get a charge out of conversations with Mario J. Maltese…I always learn something new. How I do love a good snow day! – LA Morrow
* Project Gutenberg is a library of over 70,000 free eBooks