[DECtalk] DECTalk 4.2 Alpha (fwd)

Jayson Smith jaybird at bluegrasspals.com
Tue Aug 16 18:23:33 EDT 2022


Hi,

I can hardly claim credit for the Echo II emulation. That, along with 
the whole Apple IIe emulation, is thanks to MAME. I was just the one who 
discovered that MAME, at that time MESS, could emulate the Echo II.

As for emulating Votrax, I think Mame can do at least some of that. The 
point of such a thing would be to have it available in order to emulate 
any device that uses it. For example, if anyone ever made a Braille 'N 
Speak emulator, they'd need to emulate the speech.

Jay

On 8/16/2022 5:55 PM, Blake Roberts via Dectalk wrote:
> 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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