BAS Message
March 2016

1.  Roy Allison passed away on March 1. The Summer issue of the BASS will be dedicated to him.

2.  For February we joined the AES as guests to hear Eric Blackmer talk about his thesis that the human hearing, though limited to 20 kHz on the frequency domain can still respond in some audible way to frequencies above that. Their mikes are flat to 40 kHz and have a noise floor of 20 dBA (which is quite remarkable for small diameter mikes). Some years ago Brad Meyer and David Moran (of the BAS) did a test of the audibility of a CD quality (i.e. 22 kHz bandwidth) channel when inserted in to a HiRez playback channel (published in the AES journal). After 500 or so trials, the listeners responded no better than chance. Since then their study has often been criticized for the source material, methodology, and playback system, but no one has done a study proving otherwise. Their program source was commercial HiRez recoding, however most if not all were made with microphones having a cutoff of 20 kHz or so. Earthworks has a library of 40 kHz recordings so perhaps it is time to revisit the tests. Messrs M & M may be weary of it all but I'm sure they would be glad to provide technical assistance to anyone wishing to do another round of tests—in particular the loan of the ABX box which allows easy double blind tests

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updated 3/27/16