brent@itm.UUCP (12/30/83)
A few miscellaneous audio notes: 1) Altec Lansing did indeed file Chapter 11 bankruptcy this fall. This is because of debts incurred in an acquisition of another company a few years ago. They will continue to operate, as their audio division is a steady money-maker. 2) A couple of years back, while the audio community was in heated debate about sampling rates, number of bits, etc. KEF ran a double-blind listening test at an AES convention. They introduced distortion, band-limiting, etc to a variety of signal sources. The most severe was an eighth-order elliptic low-pass cornering at 16 kHz. The results: no one could tell when it was introduced. 3) These same people, KEF, do double-blind tests at the factory the signal sources being a) a recording of a person played through KEF speakers and b) the person himself. They are getting close to complete accuracy in that listeners cannot distinguish between the two. Their findings also suggest that nobody can tell the difference if the spectrum is limited to 16 kHz. 4) Miking technique: The Detroit section did an experiment a few years back: They taped a concert in Ford Hall using three sets of identical microphones and three identical tape decks. The methods used were a) the three-point omni method b) the ORTF (German national) standard: cardiod mikes spaced 17 cm apart, at 110 degrees. i.e. positioned like ears. and c) the Blumlein method: crossed coincident bidirectional mikes. The same passages were played back before a group of critical listeners. The results: How many preferred the three-point method: 0%, the ORTF: 10%, the Blumlein method 90%. They presented this at an AES convention I attended and I agree. The Blumlein method was definitely superior. Brent Laminack ([gatech|akgua]!itm!brent)
norskog@fortune.UUCP (01/01/84)
#R:itm:-104700:fortune:1400011:000:415 fortune!norskog Jan 1 11:32:00 1984 Placing 2 mikes 17 cm apart is not a realistic simulation of human ears unless there is a skull between them with a brain case full of Jell-o (tm). :-) Seriously, I have heard rumors that more than one audio research outfit has just such a creation sitting around for experimental purposes. One is nicknamed "Mikey"! Lance Norskog Fortune Systems {hpda,harpo,sri-unix,amd70,ihnp4,allegra}!fortune!norskog
pmr@drufl.UUCP (Rastocny) (01/04/84)
Re: Ear spacing and microphones Dr. Bose has a dummy complete with torso and limbs used on the Corvette/Delco project at GM. Can anyone help with the name?