[asterisk-users] cepstral vs festival

[Brent Davidson]

John Todd wrote:
> Erik -
>    Have you found RealSpeak to be worth the cost?  Can Cepstral, with  
> the hourly $ spent on tuning, be made to be a reasonable substitute?   
> It's been a while since I did a head-to-head comparison between  
> Cepstral and (anything else) so I did a quick demo of the RealSpeak  
> Host-based telecom app:
>
>    http://www.nuance.com/realspeak/demo/  (contact data required)
>
> and the Cepstral demo:
>
>    http://www.cepstral.com/demos/
>
> I used the "Jill (default - 8khz)" for RealSpeak and "Allison  
> (default)" for the tests, and played back the same phrase:
>
>    "Congratulations. You have successfully installed and executed the  
> Asterisk open source PBX."
>
> My results: The RealSpeak sample was more clear than the Cepstral.   
> But by how much?  I should probably test with more than just that one  
> phrase, but I can't say I'd prefer RealSpeak significantly over  
> Cepstral in this extremely limited case.  Does RealSpeak get better  
> long-term test results and comprehension/retention?  I know that  
> Cepstral is $50/port - the RealSpeak pricing is un-findable, which  
> tells me that it's significantly higher than Cepstral.  (Personal  
> peeve: at least put your list pricing on the website! <grumble>)
>
> That being said, I'd really be interested in hearing if anyone has  
> done a RealSpeak-to-Asterisk conduit.  I wasn't able to quickly  
> uncover how they interact with third-party systems - is it VoIP?  A C  
> library?  Some sort of HTTP socket?  The more methods we can get  
> working with Asterisk, the better, because not every implementation of  
> a voice system has the same requirements...
>
> JT
>
> ---
> John Todd
> jtodd at digium.com        +1-256-428-6083
> Asterisk Open Source Community Director
>   
This may not be a perfectly fair comparison.  Looks like you're 
comparing the RealSpeak 8khz voice to the Cepstral default Allison which 
is NOT 8khz.  If you look on the Cepstral site you'll see "Desktop 
Voices" and "Telephony Voices".  The Cepstral Telephony voices are 8khz, 
and I suspect their quality is on par with RealSpeak.  I recently 
licensed the Allison-8Khz voice for some of the admin functions on my 
companies phone systems where I didn't want to record prompts and Flite 
was too robotic sounding.  The Allison-8khz voice is virtually 
indistinguishable from the pre-recorded Allison prompts, except for 
maybe some minor differences in inflection.  I was thoroughly impressed 
with the quality though.  For the most part it sounds like you've hired 
Allison to record custom prompts.  The Allison Desktop voice is OK, but 
sounds sort of like Allison is taking through a spinning fan blade.

When you're doing TTS comparisons be sure you're comparing apples to 
apples and not peaches to apricots.