[DECtalk] Some DECtalk history and what I think we can and can't reasonably do

Wed Aug 3 13:13:01 EDT 2011

There's always two sides to a coin, if DECtalk hadn't been purchased it
would have died. And since there was no money from anyone to work on
handicapped applications, we had to do what our customers want it or go
home. I recognize that the HLsyn work did not yield the hoped-for results
and perhaps someday it can with what we learned in our failures. But it was
a decision based on the best knowledge we had at the time and in fact also
with Dennis Klatt's work. The problems that occurred with the HL sin version
aren't of any interest to me because the version put out was in early one
and it's not the right time to pursue trying to perfect HLsyn. S
On all I can do is my best.
   As to the person that mentioned the idea of putting meaning into the
text. DECtalk actually has the ability to do some marketing and adjustment
to train achieve that by hand. Automating the system to do that is deal
beyond our knowledge and capability. Understanding what is being conveyed is
extremely extremely difficult for a computer. A simple example;"You did
that." Depending on which word you emphasize most there are three different
ways of saying this very simple sentence with dramatically different
meanings.

 Wed, Aug 3, 2011 at 12:07 PM, Alex H. <linuxx64.bashsh at gmail.com> wrote:

> **
> Well, to us,, we never really heard later versions of DT, only the classics
> from the 90's, so forgive us if we compare the new attempts to prior
> versions - it's not like we have a huge library of source code to just
> browse at will and endless samples of every version.... so... yeah.
>
> Wanna know what's been wrong with the samples and attempts posted to this
> list a few months ago for the sapi dectalk? I'll tell you.
>
> The voices were clipping and squawking, and all the voices sounded like
> they had a speech problem. Perfect Paul wasn't perfect as most of us have
> heard before. The voices themselves sound not like DECTalk at all, they also
> drop out in volume, just like a human cuz it's using HLsyn to make it sound
> more natural.
> I've heard DT 4.2cd, 4.3, 4.4, 4.61, 4.62 and 4.64. But since you've
> pointed out before that version numbers don't matter to speak, is this even
> important anyway or are we just listening to the same code with minor tweaks
> to get the various versions we know?
>
> Disable HLsyn in the new product, and it'll suck less. I like forment based
> synths, not ones that try and sound human, because I and others are used to
> classic forment non-HLsyn versions of DECTalk. True that HLsyn is still
> formant but it's trying to sound real and have human articulation, and
> knowing that I can understand why this version sounds different. It's just
> not what we're used to, that's all. Some Joe Blow off the street who has
> never heard synthesized speech can't understand Eloquence from DECTalk from
> Espeak anyways, so this point of understanding speech is a moot one.  They'd
> be better off using Cepstral or some human-sampled synths and wasting their
> hard drive space. This is being targeted at a relatively small group of
> people who have used DECTalk before and like it, so i think we're safe
> there. I'd consider giving HLsyn another shot if it was completed. But as
> always, corporate America screws everyone over in the end, and that was the
> case with Dectalk. So much so, that Fonix wanted to make FonixTalk and
> specificly try and make it sound human. The result sucks.
>
>
> Alex
> On 8/3/2011 11:17 AM, ebruckert Bruckert wrote:
>
>    First of all let me make you aware that I use DragonDictate, as I can't
> see very well and proofreading is quite painful so you'll have to forgive
> and interpret from mistakes the DragonDictate may make. It
>    I was taught about form and speech synthesis by Dennis Klatt, and by
> reading but before my involvement with him I knew next to nothing. One of
> the questions in the early days was could you achieve higher intelligibility
> by super articulation and do better than natural speech. What testing
> revealed was really two things. At normal speaking rates the answer always
> seem to be that the closer you matched to real speech the better the
> intelligibility at higher speaking rates above that which humans could
> normally achieve things were little different and I'm not going to go into
> the specifics of what we did to make things better at high speed other than
> to say they were based on knowledge of speech perception.
>      The second thing we learned is that listening to a synthesizer has a
> very fast but steep learning curve. Somewhat analogous to learning to
> understand a person with a strong dialect or speech impediment. One of the
> problems we encountered is that people often preferred the version they were
> used to over any succeeding version. But actual tests did not support the
> preference.
>      One example is the way tilt was done inside DECtalk. The original
> mechanism was a crude approximation of spectral tilt. Dennis before he died
> developed a much more accurate (meaning matching human production) tilt
> filter that was not able to be incorporated to a later date. As a point of
> interest Dennis was so dedicated that he last modified the DECtalk code 3
> days before he passed away. So the spectral tilt was changed and this
> changed what you might consider the tone control on an old radio or record
> player. That is just one of many reasons why DECtalk change slightly over
> the years.
>       The 5.0 DECtalk Incorporated the work of Prof. Ken Stevens who was
> Dennis is blessed MIT and close friend. The 5.0 code unfortunately did not
> yield the expected results, but we did learn a lot from the attempt. This
>        there are even some changes to DECtalk that would change the way it
> sounds from any particular version, such as Intonation that I am unwilling
> to revert because I know for a fact that they caused loss of information. So
> my goal is very simple I am working to create a very functional intelligible
> DECtalk to put back out, I am unwilling to try and make it sound exactly
> like any given person wants to. I have been through this before and the year
> is very sensitive and if you directly comparing two versions side-by-side
> you not testing anything but whether did the same and that is an exercise in
> futility. T
>
> Any specific issues I can address. Secondly as a word of warning to
> listeners providing feedback. The other thing we've learned is that
> listeners are excellent at deciding that something is not right, but are
> absolutely terrible at exactly pinpointing the problem. The reason for this
> is quite simple people judge the output as speech which it only kinda is, by
> this I mean that a synthesizer can make mistakes that humans cannot possibly
> do and as a consequence can't possibly recognize. An example of this is that
> after so many years of working with it I have learned to hear a foreman
> that's moving too rapidly, but most people cannot hear it. This is because
> to make life easy we try to lead nor stuff that's not important in our
> language, such as the nasal lifestyles in French or the retro flex ours in
> American English which is Sheehan have a heckuva time hearing.
>
>
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>
> --
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