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Re: Re: again about compression, actualhearing

Subject: Re: Re: again about compression, actualhearing
From: Marty Michener <>
Date: Sun, 07 Apr 2002 09:36:31 -0400
At 06:08 PM 4/6/02 -0500, you wrote:
>Marty Michener wrote:
>a bunch of interesting stuff.
>I have a few questions:
>What mics and headphones did he find with such high frequency response?
>It's not just the digital encoding that changes things, very little
>equipment is made for going above the 20k limit by any significant
>amount. Sennheiser, for instance seems to have only one mic that gets up
>there at all, the MKH 800. And it stops way short of 80khz at 50khz. And
>it's a pretty recent mic. You would also need custom mic pre's, special
>analog recorders too. Even the analog recorders have cutfilters built
>all through them in one form or another. And headphone design limits
>their upper frequency too.

HI Walt:
Excellent questions.  My only answer is, I think the mics and recorder went 
nearly flat to over 120 kHz.  My memory, only.

I have no recall of his mentioning measurements of phase shift, although in 
four hours he undoubtedly might have.  We are talking huge, expensive audio 
lab at Tufts, fed funding and no real budget limit.   Does ONR know "state 
of the art"?   I have wondered all the same things you ask here, but all I 
can recall is he had the mics custom built, and they worked to 120 kHz, and 
he use analog recording techniques (modified RTMA video machine???).

The sad details:

As this was, to my knowledge, never published (Batteau untimely death, see 
below) it is all from a verbal conversation on or about 1965.  There is 
another, interfering angle - I was introduced to D.W. Batteau by an old 
friend, Roger Payne, Post-doc from Cornell at Tufts, switching from Barn 
Owl hearing to moth hearing to whale hearing.  Roger was just about to jump 
off the academic cliff into single-handedly creating the 'save the whales' 
movement - Judy Collins, rock groups, original Humpback Record, etc.  He 
had enlisted me and Batteau for technical support of his acoustic 
research.  So, Roger was diverting DWB from his lab hearing analysis to the 
ocean, and into saving marine mammals.

I have looked his stuff up on the web, and it is all overshadowed by his 
next venture - inventing and publishing a dolphin conversation maker.  He 
published this work originally supported by ONR, as many of us did in the 
60's - basic, not applied  research, or so we thought. He published and 
demonstrated the uses of his machine. It converted human voice sounds into 
clicks or pops or whistles played over a speaker hydrophone, so that vocal 
commands by humans could come closer to dolphin's own natural 
communications, and demonstrated a much-increased training process with it.

Now comes the confused history.  The navy decided to "possess" his 
work.  The project was suddenly classified, copies of the report were 
garnered and locked up or destroyed.  You remember the late 60's, and the 
degree you believe what actually happened today must depend on how much of 
the paranoid "us and them" you believed, then and now.  The upshot is many 
liberals claimed that the navy was using it to train dolphins to carry 
bombs into enemy places.  he growing environmental movement lapped it all 
up.  Now "they" are coming to tap our phones, even kill us if we know too 
much!  They also claimed that when Batteau was found drowned, in Hawaii, 
about 1968, that it had sinister "them" implications.  This discussion was 
whispered even on many college faculty meetings, because Batteau by that 
time was in a major media battle to prevent the Navy ever using dolphins 
for military purposes, including activists that went to jail for midnight 
dolphin releases from federal projects.  Very exciting stuff.  But some 
have even claimed Batteau's wife's boyfriend did it.  All word of mouth. It 
was hard to even puzzle it all over. Nothing was ever proven about the 
death, and it is still listed as accidental - a guy out for a morning run 
and swim around sunrise. We just lost a really bright guy, but, of course 
we won the war.  ( ;^))

Sorry, for so much diversion, but it explains the never published part.

>So, maybe what we are talking about is actually sound that's much lower
>frequency, but precise measurement of the timing of the arrival of the
>wavefront is how it's done. Phase shift calculations in other words.
>Yes, digital can mess this up, but the flip side is that a cutfilter
>working perfectly should not. Most real life filters produce some phase
>shift, however, which is a timing change. I wonder if there has been any
>examination on just what was getting through his system? What it's phase
>shift was and so on.
>And if it's phase shift that's used even we old geezers can do it. I can
>certainly localize a sound precisely still.

Not only do analog filters produce phase shift, but our digital editing 
filters do as well.  I agree with all you said, but I specifically recall 
Batteau telling me - when you impose analog filters in the headphone 
output, most of the 3D beamforming process is disrupted.  The up-down and 
front back stuff, probably not the methods we use to localize sounds from a 
distance in the woods or field.

I will try to contact Roger and ask about these studies.  I haven't seen 
him in decades.  If anyone on the list has his email, and would send it to 
me privately, I think he is living now in Vermont, or was it England?  I 
could probably find out from his ex-wife, Katy Boynton Payne, at Cornell, 
and now of elephant communication fame.

Marty Michener
MIST Software Associates
75 Hannah Drive, Hollis, NH 03049

coming soon : EnjoyBirds bird identification software.


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