[OT?] what's a FPGA?

Jerry Avins wrote:
> rickman wrote:
> 
>   ...
> 
>> BTW, I know you want to do it "your way", but sampling at 44 kHz will
>> not give you any extra useful information that you won't get at 8 kHz.
>> The phone company is not dumb and they realized a long time ago that
>> the range of frequencies required to carry intelligible voice is less
>> than 4 kHz.  The higher frequencies do not add much to the picture, but
>> will require a lot more power to analyze.  Have you found any content
>> in the higher frequencies that others have not?
> 
> 
> I find that intelligibility of speech -- even screechy soprano speech -- 
> is hardly impaired by my hearing loss. I can't hear the top two notes on 
> a piano. Now that's a brick-wall filter!

/ begin chuckle
I'll see your "normal" hearing loss and raise you my *abnormal* loss
/ end chuckle

I look for wider than telco land line bandwidth for 2 sets of reasons:

A1. I've read articles saying telco speech is "intelligible" but it is
     easier if higher frequencies available. The distinguishing features
     of consonants are in the higher frequencies. *HUMANS* automatically
     resolve ambiguities based on context (several layers of?).
A2. If I read correctly, speech recognition tends to use _AT MOST_ the
     first three formants (~150 -> ~1300 Hz) for vowels and presumably
     some similar range for consonants.

B. I have a "good" ear and a *BAD* ear ;)
    "Bad ear" degraded due to scars on ear drum and nerve damage related
     to childhood ear infections.
B1. If enough points are recorded, the response of my "bad ear"
     resembles a "picket fence" [Guess what a lifer seargant said when I
     took an *ENLISTMENT* physical with a bunch of _DRAFTEES_ during
     Viet Nam ;]
B2.





> 
> Sampling at 44.1 will make recursive filters easier and transversal 
> filters harder. Given Richard's view that he needs linear phase, 44.1 is 
> asking for trouble. In his place, though I would plan to sample at 
> around 12 KHz or, if it's enough simpler, 22.05. You can't tell that the 
> high end isn't useful unless you have it.
> 
> Jerry

"Richard Owlett" <rowlett@atlascomm.net> wrote in message 
news:123dj14mgtn4d44@corp.supernews.com...
> Jerry Avins wrote:
>> rickman wrote:
>>
>>> BTW, I know you want to do it "your way", but sampling at 44 kHz will
>>> not give you any extra useful information that you won't get at 8 kHz.
>>> The phone company is not dumb and they realized a long time ago that
>>> the range of frequencies required to carry intelligible voice is less
>>> than 4 kHz.  The higher frequencies do not add much to the picture, but
>>> will require a lot more power to analyze.  Have you found any content
>>> in the higher frequencies that others have not?
>>
>>
>> I find that intelligibility of speech -- even screechy soprano speech -- 
>> is hardly impaired by my hearing loss. I can't hear the top two notes on a 
>> piano. Now that's a brick-wall filter!
>
> I look for wider than telco land line bandwidth for 2 sets of reasons:
>
> A1. I've read articles saying telco speech is "intelligible" but it is
>     easier if higher frequencies available. The distinguishing features
>     of consonants are in the higher frequencies. *HUMANS* automatically
>     resolve ambiguities based on context (several layers of?).

This is easy to verify by having someone say a long set of random letters over 
the phone while you try to right them down.  You might be surprised how poorly 
the accuracy is, especially in discriminating pairs such as s/f, v/z, p/t, etc.. 
This problem is probably also part of the reason the military uses the "alpha, 
bravo, charlie..." alphabet for spelling out things.  So while the human brain 
does a very good job at understanding normal speech from context clues over a 
limited frequency channel, additional high frequencies make it much easier on 
the brain (and hence less tiring for long conversations).  There is certainly a 
matter of diminishing returns, but in my experience, even extending from the 
normal phone high frequency response to 4-5 kHz makes a substantial difference.