[DECtalk] DECTalk 4.2 Alpha (fwd)

[Blake Roberts]

I agree with Don about not seeing a point in emulating a Votrax speech 
synthesizer. I know it is sometimes possible to emulate a hardware 
speech synthesizer. About a decade ago, the owner of this list (Jayson) 
managed to emulate the Echo2 speech synthesis card manufactured by 
Street Electronics so that a virtual Apple IIEE can talk. That emulation 
had value/a point because those interested can use old Apple2E discs in 
combination with a specific Apple2 emulator and hear the screens spoken 
via Echo2 speech. Mr. Smith's emulation of the Echo2 hardware speech 
synthesizer was/is impressive to me because it sounds almost exactly 
like the hardware speech card.


However, I don't see any practical value in someone "emulating" a Votrax 
speech synthesizer. I have heard one or more Votrax synthesizers in the 
audio demonstrations created by Dennis Klat before his passing in the 
1980's. Hearing an emulated Votrax synthesizer, from my perspective,  
would be equivalent to someone deciding: "I want to remind myself of 
what the Braille N Speak voice chip sounded like." I don't remember what 
speech synthesizer hardware the Blazie Engineering Braille N Speak used, 
but I do remember I could not stand the voice because it always sounded 
monotone/boring to my ears.



Blake




On 8/16/2022 2:12 PM, Don wrote:
> On 8/16/2022 5:19 AM, joshknnd1982 at gmail.com wrote:
>> The votrax SE02, the one used in many notetakers and speech 
>> synthesizers. Is
>> there any emulators for that one?
>
> I assume you mean the SC-02 aka SSI-263.
>
> Votrax's approach to synthesis was entirely analog.
>
> The original boardset consisted of 4 (?) sizeable "modules"
> (about 2.5 x 6" each) *potted* to hide their contents (of
> course, that's not an effective way of protecting a design as
> anyone can opt to remove the encapsulation and then it's
> just a set of circuit boards using COTS components!)
>
> The modules were color-coded: red, green, beige and grey.
> They served different functions: delay, fricative, vocal
> tract and transition.  Optional modules provided a serial
> interface and "stored phrases" (via ROMs).  You could also
> hook up a (special) keyboard to control the unit without
> a computer being present.
>
> The whole unit was a bit larger than a USFF but a bit smaller
> than a SFF PC.  Cost was ~$1000.
>
> All of the waveform generation was done with analog circuitry.
>
> Also note that the device only created "phonemes".  It was
> the responsibility of the device driving it (e.g., a computer)
> to figure out which phoneme to utter and in what sequence,
> how to apply prosody, etc.
>
> Devices like the Type n Talk, Personal Speech, Microvox,
> Intex Talker, etc. augmented the "waveform generator"
> (Votrax) with a small microprocessor that applied a canned
> set of rules to determine which phonemes/intonation to
> generate to render a particular set of letters into speech.
>
> The algorithm used seemed to be the NRL ruleset with, possibly,
> some minor optimizations (exception word dictionaries, etc.)
> AFAICT, the only competing "simple" letter-to-phoneme ruleset
> available at that time was McIlroy's.
>
> [Most of these were remarkably bad -- estimates of ~60% accuracy
> were not uncommon -- as they couldn't do much high-level parsing
> of the input, complex sentence analysis, etc.]
>
> The VS6 could sing (if you manipulated the data sent to it,
> appropriately -- on a per-phoneme basis!).  I heard a VS6.3
> speak convincing German!
>
> With that as background, the SC-01 and SC-02 were "integrated"
> versions of the same basic technology.  Switched capacitor filters
> were used to get everything onto a chip.  But, the voice quality
> was largely the same.
>
> We used to joke that you needed 12 inches of concrete to block
> out the sound of the voice!
>
> By contrast, DECtalk (KlattTalk, MITalk, etc.) is a pure software
> approach.  The filters/resonators are implemented in the digital
> domain with the resulting "speech" happening at the very end of
> the process where the DIGITAL waveform is converted to analog form.
>
> Also, the letter-to-sound rules are implemented *in* the synthesizer
> instead of being the responsibility of some external "program".
>
> While it could be possible to write an emulator for one of the
> votrax designs (i.e., map each analog filter into a corresponding
> digital/software implementation and the various digital controls
> of those filters into their corresponding equivalents), I can't
> see any value to doing so other than as a monument to oneself
> ("I didn't have anything important to do so I've resurrected
> an obsolete technology instead of buying an SSI-263 on eBay")
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