Creating a Computer Voice That People Like | Hacker News Reader

Creating a Computer Voice That People Like

nytimes.com

57 pointsdnetesn25 comments

Amusingly the biggest problem here is english itself, and the way it is amazingly irregular in all its pronounciations, and how a few letters can change an entire word (constable, unstable).

The article shortly mentions the technology that uses voice sample databases, without mentioning its primary example: Vocaloids.

With vocaloid technology digital speech synthesis works amazingly well and is used to create entire songs ( here's a video of a voice bank donor singing together with her vocaloid: https://youtu.be/JfW0glLj2pE?t=74 ; here's an example of casual TTS for chat that sounds silly, but is incredibly clear to understand: https://youtu.be/R8OoadkjO8Q?t=20 ). However this only works well for japanese (voice bank size: ~100 samples), since it is astonishingly regular (i.e. spelling maps almost 1:1 to pronounciation), while in english there is almost no regularity whatsoever, so to replicate the same, voice banks need to be 1000 samples and more big.

There are still a limited number of sounds in English. Including a dictionary that had phonetic pronunciations seems like it should be sufficient to avoid the constable/unstable problem.

It's not just pronounciation of specific words though, it's also combinations of words, and abbrevations like "would've". English basically consists entirely of special cases, while in japanese you can straight-up just match the written letters to the sound and get it right in most cases. In fact, i can tell you the exceptions in this post right quick: Sometimes the u sound is swallowed when it would be more comfortable to say the word without it. "Wo" is almost always pronounced as "o". "Ha" is very often pronounced as "wa" due to a specific grammatic rule. Now try listing all the exceptions to english pronounciation. :)

You can deal with the irregularity of spelling by using a pronouncing dictionary, which has the correct pronunciation of every word in a lexicon. For example, CMU has the CMU Pronouncing Dictionary:

http://www.speech.cs.cmu.edu/cgi-bin/cmudict

Spelling irregularities are fully taken account of. But a problem is heteronyms, where the same spelling is pronounced in two different ways depending on the meaning, like English initial stress derivations

https://en.wikipedia.org/wiki/Initial-stress-derived_noun

A pronouncing dictionary will record each of the options but might not provide a way to determine which one is correct in a particular context.

Combinations of words, as you mentioned, do pose problems for speech synthesis because of suprasegmentals, where for natural speech you might need to adjust features of one word because of the presence of others, for a variety of linguistic reasons.

https://en.wikipedia.org/wiki/Prosody_%28linguistics%29

Japanese has suprasegmental issues too, so you can't expect to make realistic speech synthesis easy just by synthesizing a language with a regular orthography and a simple sound structure. Also, imagine trying to create text-to-speech for Japanese texts written in kanji rather than kana; you'd have irregularity problems in some ways even more challenging than English orthography presents!

https://en.wiktionary.org/wiki/%E7%94%9F#Kanji

A pronouncing dictionary does not help you when people invent new words or import new words from a different language, in which case readers familiar with the subject at hand might identify the pronounciation from their familiarity with the source language or subject.

Unless, of course, you have an AI attached to your TTS that can understand the context in a similar way.

Depending on the context, you could potentially just include the pronunciation of all the new words in the context a video game set in a fictional setting.

The script/site below is able to transcribe whole English texts into phonetics. It does take word context into account (e.g. "the" becomes "thee" if it is before a word starting with a vowel). Just checked "We've" and it does manage to produce a good phonetics transcription.

http://lingorado.com/ipa/

If you are talking about phonological categories, then you are almost certainly correct. However, somewhere between choosing to produce certain phonemes and the actual sounds you produce, there's some process (maybe just the physics of your vocal tract) that gives rise to tons of variation in what linguistically is a single phonological category. IPA doesn't capture that.

Of course, IPA does capture unstable vs constable.

I've always found it odd that the video game industry hasn't put as much focus on improving speech synthesis as they do on 3D graphics. They would be the ones to benefit the most from more natural text-to-speech.

Seems to me that back when games used to be in text, you got to have more elaborate storylines because the developers and writers themselves could just add and improve the dialogue at any time. See Planescape: Torment [1], regarded to have one of the most complex stories in a game, with enough dialogue to rival a novel, but most of it is in text. Same for Star Control 2 [2] which was the inspiration behind Mass Effect.

Now, when everyone wants to be Hollywood and voice-acting is the norm, and expected by players for a game to be considered high-quality, stories are locked in to whatever was recorded in the studio at the time. This is also probably the reason for the discrepancy between the dialogue choices you see onscreen, versus what your character actually says (such as in Mass Effect and Fallout 4 and many others, where you just to get choose between something like "Joke" or "Threaten" and it sometimes spawns a very unexpected chain of conversation.)

Better speech synthesis would not only empower solo developers to write engrossing stories and complex dialogues from the comfort of their bedrooms, like they used to, it'd also open up better player customization in RPGs and online games, when whatever you type would be spoken to other players in your preferred voice.

[1]: https://en.wikipedia.org/wiki/Planescape:_Torment

[2]: https://en.wikipedia.org/wiki/Star_Control_II

It would be convenient, certainly, the same way a robot kitchen would be convenient. But it turns out human chefs aren't all that expensive compared to an equally competent robot chef, at least for the foreseeable future.

The video game industry already has lifelike speech available to it, for a cost. Lifelike 3D graphics on the other hand don't exist at any cost.

But with human voice actors, you can't modify the dialogue in your game, or change/improve the part of the story that's tied to that dialogue, without scheduling new recording sessions.

That can get expensive and actors aren't always going to be available (which is another problem when you're trying to make sure you get the same voices for DLC & sequels etc.)

Yes, I understand why it would be nice to have arbitrary lifelike synthesizable voice. But hiring a voice actor currently gets you 90% of the way "there" (wherever "there" is) at a tiny, tiny, minuscule fraction of the cost of personally developing the entire future of speech synthesis.

Having grown up with various levels of automated speech, today's speech synth is really good. At times it takes a few seconds of listening to find a "tell" that lets you know it's not a person or a pre-recording of a person.

Here's some examples of what I grew up with for comparison:

-https://www.youtube.com/watch?v=0ccKPSVQcFk

-https://www.youtube.com/watch?v=rR0Ofu0M53g

-https://youtu.be/4S3G3veop2w?t=102

-https://www.youtube.com/watch?v=ginShVeGpGY

and then suddenly in the last few years you get Siri.

With a few more rules, I wouldn't even mind if modern voices read entire books to me. They need to make more pauses, take breaths for example, or they can be exhausting to listen to...but I have the sense that we're pretty close.

Of the examples you gave, the first one is a real human voice run though a vocoder, and the last one is a real human voice sampled at a really crappy sample rate and played back using hardware never intended for digital sampled audio.

Speech synthesis is a spectrum of technologies. In the early days there really wasn't much difference between recording somebody and playing back, and using chopped up phoneme recordings or words and reordering to produce speech.

It's kind of like those robot voices used by telephone companies and answering machines for years, they're just a prerecording of somebody saying some words and numbers and the machine connects them back in the appropriate sequence.

At finer granularity you simply record somebody saying phonemes and reconstruct them back into a voice that can say pretty much anything. Alter pitch and you can have it ask questions or sing. This technique has been around in some way for decades.

Here's an excellent interview with the guy who did much of the foundational work in the field. http://ataripodcast.libsyn.com/antic-interview-101-forrest-m...

I always liked the original, Klatt-based synthetic voices that actually sounded like vocoders. I would think we could avoid the uncanny valley by creating synthetic voices that deliberately sound like synthetic voices.

I still find Watson's voice a little unsettling. It's almost like the speaker is smiling to me all the time, like the black-suited man who recruits Deadpool in Deadpool.

As an aside, if anyone is wondering why that guy looked so familiar it might be because he played the always-smiling alien Teb in Galaxy Quest.

Edit: Funny enough, the "uncanny valley" cadence of the Thermians' English reminded me quite a bit of speech synthesis. I now wonder if that's where they got their inspiration.

I "heard" Stephen Hawking remains with his stilted American-accented computer voice instead of using a modern computer voice because people recognize it as him. That old voice is hard for me to clearly understand, as I was listening to his recent salutary message on gravitation waves.

"Andy Aaron, an IBM Research researcher, said mispronunciation was the “biggest problem” in preparing Watson for “Jeopardy!”"

Ironically I'd say that mispronunciation is probably a trait that would make it seem more human.

The irony is that photorealistic imagery with three orders of magnitude bandwidth than voice has been essentially solved already. If it was solved, they would have replaced expensive voice actors in CGI movies.

One of the reasons the photorealistic imagery with those badly synchronized lips works is because the voice makes it authentic.

Remove the voice and we fall into the uncanny valley.

https://en.wikipedia.org/wiki/Majel_Barrett

Done

In order to spare some of you a click: this lady was the talent behind the voice interfaces in Star Trek.

Majel Barrett-Roddenberry (first name pronounced /ˈmeɪdʒəl/; born Majel Leigh Hudec;[1] February 23, 1932 – December 18, 2008) was an American actress and producer. She is best known for her role as Nurse Christine Chapel in the original Star Trek series, Lwaxana Troi on Star Trek: The Next Generation and Star Trek: Deep Space Nine, and for being the voice of most onboard computer interfaces throughout the series. She was also the wife of Star Trek creator Gene Roddenberry.

The Talking Moose circa 1987 using the Macintalk voice of 'Fred'-- what more could we need?

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