Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!pasteur!ucbvax!decwrl!pyramid!octopus!avsd!govett
From: govett@avsd.UUCP (David Govett)
Newsgroups: sci.crypt
Subject: Re: Understanding scrambled speech without a descrambler
Message-ID: <118@avsd.UUCP>
Date: 21 Apr 88 16:54:40 GMT
References: <1988Apr20.075217.761@utzoo.uucp>
Organization: Ampex Advanced Technology Division, Redwood City, CA
Lines: 18

in article <1988Apr20.075217.761@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) says:
> Xref: octopus rec.ham-radio:1388 sci.crypt:1137
> 
>>    One of my favorite daydreaming topics is how humans might
>>    develop  the  ability  to  understand  scrambled  speech,
>>    without using a  descrambler...
> 
> There are instances of this on the record.  In mid-WW2, Bell Labs
> demonstrated that about half of a conversation using the then-current
> A-3 scrambler -- used by Roosevelt and Churchill, among others --
> could be understood by the unaided ear, with some practice.  It is
> really quite hard to scramble speech well with pre-digital techniques.
> There is too much redundancy in it.
> 


Speaking of "on the record," I remember reading about an engineer
at Columbia Records, I think, who could recognize any piece of 
classical orchestral music by the groove pattern on the disk.