[net.audio] odds and ends

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?