Richard Owlett wrote:> Jerry Avins wrote: > >> Randy Yates wrote: >> >> >>> Sometimes it is good to simplify, but I don't think this is one >>> of them. >> >> >> >> That's why I thanked you for calling me on it, and described myself as >> having "oversimplified". >> >> Jerry > > > Mr. turner referenced http://mathworld.wolfram.com/SincFunction.html > which shows that "authorities" have used both definitions. > > [ posted only to prove that I do follow links, even if I tend to fade in > threads I've triggered ;]In DSP, the form with pi is more generally useful and far more common. (I only argue with Randy when he's wrong!) :-) Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
To 'sinc' or not to 'sink'
Started by ●January 11, 2004
Reply by ●January 12, 20042004-01-12
Reply by ●January 12, 20042004-01-12
Hello Richard, Actually I did a lot of speech processing back during the 90s, so I can offer some help. Typically with characterizing speech there are many methods. So don't get too hung up on any one. But generally speech is broken up into overlapping frames where the frame duration is picked to basically let the speech during that time be approximately constant. For example you may let your frames be 30 mSec in duration but you start frames every 10 mSec. Yes there is a lot of overlap but that is okay. Then each frame analyzed for whatever you are looking for. Example you may simply want the energy for each frame. This can help with silence detection. Also you can look at the count of zero crossings. This is useful for helping to decide when speech is voiced (i.e., are the vocal chords vibrating?) or not. Ess sounds are not voiced for instance. And you may be trying to fit a vocal tract model, so you may want to solve for the model's coefs. These can be the autocorrelation, the lpc, or the reflection coefs. Also sometimes formant identification is done with various fft methods. Commonly a cepstral method is used. Here are some good references for these methods: Rabiner & Schafer "Digital Processing of Speech Signals" Papamichalis "Practical Approaches to Speech Coding" Rowden "Speech Processing" Curious what application do you have in mind or are you just looking to learn about this? If you have a particular app, we may be able to point to specific solutions. Clay
Reply by ●January 12, 20042004-01-12
Richard Owlett <rowlett@atlascomm.net> writes:> Jerry Avins wrote: > >> Randy Yates wrote: >> >>> Sometimes it is good to simplify, but I don't think this is one >>> of them. >> That's why I thanked you for calling me on it, and described myself >> as >> having "oversimplified". >> Jerry > > Mr. turner referenced http://mathworld.wolfram.com/SincFunction.html > which shows that "authorities" have used both definitions.So they have. That's a new one on me (or maybe I forgot). Thanks Richard. -- % Randy Yates % "...the answer lies within your soul %% Fuquay-Varina, NC % 'cause no one knows which side %%% 919-577-9882 % the coin will fall." %%%% <yates@ieee.org> % 'Big Wheels', *Out of the Blue*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 12, 20042004-01-12
Jerry Avins <jya@ieee.org> writes:> [...] > (I only argue with Randy when he's wrong!) :-)You mean, like, every other post? :*) -- % Randy Yates % "...the answer lies within your soul %% Fuquay-Varina, NC % 'cause no one knows which side %%% 919-577-9882 % the coin will fall." %%%% <yates@ieee.org> % 'Big Wheels', *Out of the Blue*, ELO http://home.earthlink.net/~yatescr
Reply by ●January 13, 20042004-01-13
"Richard Owlett" <rowlett@atlascomm.net> wrote in message news:10063q9gbm3a041@corp.supernews.com...> Mr. turner referenced http://mathworld.wolfram.com/SincFunction.html > which shows that "authorities" have used both definitions.Hello Richard, It is okay to refer to me as Clay. Mr. Turner sounds so formal and putoffish. I'm a pretty easy going guy who gets dirty on weekends playing with horses. I've been known to do my share of pasture skiing. And the multiple defn thing with the Sinc function is just the start. There are several "standard" conventions for scaling the Fourier transform. If you recall there are at least four standard ways to scale Maxwell's equations, but you still end up with constants somewhere. So it is the same situation with the constant pi in the Sinc function and the Fourier transform. In the case of the Sinc function, the scaling just set the zeros of the function to be at multiples of unity instead of multiples of pi. Convenient for interpolating sampled data. And of course there is no zero at the origin. This value is found by L'Hospital's rule.> > [ posted only to prove that I do follow links, even if I tend to fade > in threads I've triggered ;] >I'm sure most go and look at the links even if they don't comment on them. And I figured that since you move on to the next question that your last one must have been answered. Clay
Reply by ●January 13, 20042004-01-13
Richard Owlett wrote:> Jerry Avins wrote: > >> Randy Yates wrote: >> >> >>> Sometimes it is good to simplify, but I don't think this is one >>> of them. >> >> >> That's why I thanked you for calling me on it, and described myself as >> having "oversimplified". >> >> Jerry > > Mr. turner referenced http://mathworld.wolfram.com/SincFunction.html > which shows that "authorities" have used both definitions. > > [ posted only to prove that I do follow links, even if I tend to fade > in threads I've triggered ;]If you look carefully this isn't quite what they say.. sinc(x)=sin(x)/x (as I was always taught in my maths, physics and EE lectures) The alternative definition given here uses a pi suffix (which I cannot reproduce in a usenet post). Of course wolframs word ain't necessarily the final word on this issue. Other "authorities" (such as the author of Clays second link) might well have defined.. sinc(x)=sin(pi.x)/(pi.x) which is a darned shame IMO, considering how much mathematicians, scientists and engineers value precision. Now nobody knows for sure what the heck sinc is, so it's best to avoid using it altogether. I wish whoever started this trend chose a different name for the pi version. Regards -- Adrian Hey
Reply by ●January 14, 20042004-01-14
Clay S. Turner wrote:> Hello Richard, > Actually I did a lot of speech processing back during the 90s, so I can > offer some help. Typically with characterizing speech there are many > methods. So don't get too hung up on any one.[SNIP]> Curious what application do you have in mind or are you just looking to > learn about this? If you have a particular app, we may be able to point to > specific solutions. >Primarily, I'm just generally curious. My current "bout of interest" was triggered by looking for 'command and control' voice recognition software. [My pastor and a member of the congregation have significant sight problems.] I'm disappointed in what seems to be available. There seems to be *less* available now than ~20 yrs ago [ on a relative scale ]. It seems there is only one currently available commercial package -- Dragon Naturally Speaking in misc editions. It is MUCH too oriented to continuous speech. Great for dictating "great american novel", but otherwise useless IMHO ;{ A secondary frustration is that much too much processing horsepower and a much too ideal acoustic environment seems to be required. I have a "gut feel" that something is intrinsically wrong with the current approach to speech recognition. EG Humans have no problem "recognizing" a wide variety of accents. Lossy compression yields intelligible speech. Having no academic or other reputation to risk, I wish to 'ask' questions of a [shall we say] aberrant nature. There are two areas in which I think I *MAY* have a chance of contributing something useful: 1. Acoustic environment Recent comments on "spectral subtraction" seem to indicate that there is a possibility that I might perhaps may be thinking in a useful direction [ did I include enough 'weasel words' ;?] 2. Speaker independence This is a lower probability, but I suspect investigation of *WHY* lossy speech compression is intelligible may prove fruitful. POSSIBLY OT Can anyone point me to a *WINDOWS* program/DLL that accepts a WAV file and yields a stream of "characters" representing allophones &/or phonemes?
Reply by ●January 15, 20042004-01-15
On Sun, 11 Jan 2004 15:22:59 -0600, Richard Owlett <rowlett@atlascomm.net> wrote:>What is 'sinc' function and why is it important. > >First response of "google" is "Sisters in Crime Internet Chapter" ;{ > >OK, I did find a site with plot of 'sinc' which resembled a 'cosine >with decreasing amplitude' -- The amplitude at 0 WAS 1 and decreased >from there ;] > >Actually I suspect I need to know more about "windowing". >Any references besides a book coming out in March ;>Hi Richard, there's a decent two-part tutorial on windows at: Part I: http://www.e-insite.net/tmworld/index.asp?layout=issueTOC&pubdate=6/1/1998 I just noticed the website now requires your E-mail address before they'll give the Part I article. Part II can be found at: http://www.reed-electronics.com/tmworld/index.asp?layout=article&articleid=CA187573&rid=0&rme=0&cfd=1 Good Luck Rich, [-Rick-]
Reply by ●January 15, 20042004-01-15
Rick Lyons wrote:> On Sun, 11 Jan 2004 15:22:59 -0600, Richard Owlett > <rowlett@atlascomm.net> wrote: > > >>[SNIP] >>Actually I suspect I need to know more about "windowing". >>Any references besides a book coming out in March ;> > > > Hi Richard, > > there's a decent two-part tutorial on windows at: > > Part I: > > http://www.e-insite.net/tmworld/index.asp?layout=issueTOC&pubdate=6/1/1998 > > I just noticed the website now requires your E-mail > address before they'll give the Part I article. > > Part II can be found at: > > http://www.reed-electronics.com/tmworld/index.asp?layout=article&articleid=CA187573&rid=0&rme=0&cfd=1 >A totally unbiased opinion ;? [ actually I liked it] I'm wondering if a rectangular window might be fine for what I'm doing at the moment as I was looking at logical ways to combine data in some number of adjacent bins. My sample rate is intrinsically fixed at 4 to 10 times Nyquist.
Reply by ●January 15, 20042004-01-15
On Thu, 15 Jan 2004 07:53:36 -0600, Richard Owlett <rowlett@atlascomm.net> wrote:>Rick Lyons wrote: >> On Sun, 11 Jan 2004 15:22:59 -0600, Richard Owlett >> <rowlett@atlascomm.net> wrote: >> >> >>>[SNIP] >>>Actually I suspect I need to know more about "windowing". >>>Any references besides a book coming out in March ;> >> >> >> Hi Richard, >> >> there's a decent two-part tutorial on windows at: >> >> Part I: >> >> http://www.e-insite.net/tmworld/index.asp?layout=issueTOC&pubdate=6/1/1998 >> >> I just noticed the website now requires your E-mail >> address before they'll give the Part I article. >> >> Part II can be found at: >> >> http://www.reed-electronics.com/tmworld/index.asp?layout=article&articleid=CA187573&rid=0&rme=0&cfd=1 >> > >A totally unbiased opinion ;? [ actually I liked it] >I'm wondering if a rectangular window might be fine for what I'm doing >at the moment as I was looking at logical ways to combine data in some >number of adjacent bins. My sample rate is intrinsically fixed at 4 to >10 times Nyquist.Hi Richard, ah shoot. I'm not sure what you're doing. A rectangular window is the same as not windowing at all. [-Rick-]
