[DECtalk] Some DECtalk history and what I think we can and can't reasonably do
Alex H.
linuxx64.bashsh at gmail.com
Wed Aug 3 13:38:00 EDT 2011
I, too, hope that HLsyn eventually will be a viable option and we could
use the old method or HLsyn if we wanted, maybe for reading long texts
and so on. It's a great idea and theory but just isn't mature enough at
this point.
Alex
On 8/3/2011 1:13 PM, ebruckert Bruckert wrote:
> 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
> <mailto: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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